Merge pull request #516 from ethcore/sync

Better memory management
2016-02-27 15:54:19 +01:00 · 2016-02-27 15:54:19 +01:00 · b3f09596b1
commit b3f09596b1
parent db9774fb62 10ef7123c4
16 changed files with 297 additions and 122 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -14,6 +14,7 @@ dependencies = [
 "ethsync 0.9.99",
 "fdlimit 0.1.0",
 "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "number_prefix 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "rustc-serialize 0.3.18 (registry+https://github.com/rust-lang/crates.io-index)",
 "time 0.1.34 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@ -255,6 +256,7 @@ dependencies = [
 "env_logger 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "ethcore 0.9.99",
 "ethcore-util 0.9.99",
+ "heapsize 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
 "log 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
 "rand 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
 "time 0.1.34 (registry+https://github.com/rust-lang/crates.io-index)",
@ -541,6 +543,14 @@ dependencies = [
 "libc 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

+[[package]]
+name = "number_prefix"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num 0.1.31 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "odds"
 version = "0.2.12"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -20,6 +20,7 @@ ethcore-rpc = { path = "rpc", optional = true }
 fdlimit = { path = "util/fdlimit" }
 daemonize = "0.2"
 ethcore-devtools = { path = "devtools" }
+number_prefix = "0.2"

 [features]
 default = ["rpc"]
--- a/ethcore/src/block_queue.rs
+++ b/ethcore/src/block_queue.rs
@ -28,6 +28,31 @@ use service::*;
 use client::BlockStatus;
 use util::panics::*;

+known_heap_size!(0, UnVerifiedBlock, VerifyingBlock, PreVerifiedBlock);
+
+const MIN_MEM_LIMIT: usize = 16384;
+const MIN_QUEUE_LIMIT: usize = 512;
+
+/// Block queue configuration
+#[derive(Debug)]
+pub struct BlockQueueConfig {
+	/// Maximum number of blocks to keep in unverified queue.
+	/// When the limit is reached, is_full returns true.
+	pub max_queue_size: usize,
+	/// Maximum heap memory to use.
+	/// When the limit is reached, is_full returns true.
+	pub max_mem_use: usize,
+}
+
+impl Default for BlockQueueConfig {
+	fn default() -> Self {
+		BlockQueueConfig {
+			max_queue_size: 30000,
+			max_mem_use: 50 * 1024 * 1024,
+		}
+	}
+}
+
 /// Block queue status
 #[derive(Debug)]
 pub struct BlockQueueInfo {
@ -37,6 +62,12 @@ pub struct BlockQueueInfo {
 	pub verified_queue_size: usize,
 	/// Number of blocks being verified
 	pub verifying_queue_size: usize,
+	/// Configured maximum number of blocks in the queue
+	pub max_queue_size: usize,
+	/// Configured maximum number of bytes to use
+	pub max_mem_use: usize,
+	/// Heap memory used in bytes
+	pub mem_used: usize,
 }

 impl BlockQueueInfo {
@ -48,7 +79,8 @@ impl BlockQueueInfo {

 	/// Indicates that queue is full
 	pub fn is_full(&self) -> bool {
-		self.unverified_queue_size + self.verified_queue_size + self.verifying_queue_size > MAX_UNVERIFIED_QUEUE_SIZE
+		self.unverified_queue_size + self.verified_queue_size + self.verifying_queue_size > self.max_queue_size ||
+			self.mem_used > self.max_mem_use
 	}

 	/// Indicates that queue is empty
@ -68,7 +100,9 @@ pub struct BlockQueue {
 	deleting: Arc<AtomicBool>,
 	ready_signal: Arc<QueueSignal>,
 	empty: Arc<Condvar>,
-	processing: RwLock<HashSet<H256>>
+	processing: RwLock<HashSet<H256>>,
+	max_queue_size: usize,
+	max_mem_use: usize,
 }

 struct UnVerifiedBlock {
@ -106,11 +140,9 @@ struct Verification {
 	bad: HashSet<H256>,
 }

-const MAX_UNVERIFIED_QUEUE_SIZE: usize = 50000;
-
 impl BlockQueue {
 	/// Creates a new queue instance.
-	pub fn new(engine: Arc<Box<Engine>>, message_channel: IoChannel<NetSyncMessage>) -> BlockQueue {
+	pub fn new(config: BlockQueueConfig, engine: Arc<Box<Engine>>, message_channel: IoChannel<NetSyncMessage>) -> BlockQueue {
 		let verification = Arc::new(Mutex::new(Verification::default()));
 		let more_to_verify = Arc::new(Condvar::new());
 		let ready_signal = Arc::new(QueueSignal { signalled: AtomicBool::new(false), message_channel: message_channel });
@ -133,7 +165,7 @@ impl BlockQueue {
 				.name(format!("Verifier #{}", i))
 				.spawn(move || {
 					panic_handler.catch_panic(move || {
-					  BlockQueue::verify(verification, engine, more_to_verify, ready_signal, deleting, empty)
+						BlockQueue::verify(verification, engine, more_to_verify, ready_signal, deleting, empty)
 					}).unwrap()
 				})
 				.expect("Error starting block verification thread")
@ -149,6 +181,8 @@ impl BlockQueue {
 			deleting: deleting.clone(),
 			processing: RwLock::new(HashSet::new()),
 			empty: empty.clone(),
+			max_queue_size: max(config.max_queue_size, MIN_QUEUE_LIMIT),
+			max_mem_use: max(config.max_mem_use, MIN_MEM_LIMIT),
 		}
 	}

@ -340,8 +374,26 @@ impl BlockQueue {
 			verified_queue_size: verification.verified.len(),
 			unverified_queue_size: verification.unverified.len(),
 			verifying_queue_size: verification.verifying.len(),
+			max_queue_size: self.max_queue_size,
+			max_mem_use: self.max_mem_use,
+			mem_used:
+				verification.unverified.heap_size_of_children()
+				+ verification.verifying.heap_size_of_children()
+				+ verification.verified.heap_size_of_children(),
+				// TODO: https://github.com/servo/heapsize/pull/50
+				//+ self.processing.read().unwrap().heap_size_of_children(),
 		}
 	}
+
+	pub fn collect_garbage(&self) { 
+		{
+			let mut verification = self.verification.lock().unwrap();
+			verification.unverified.shrink_to_fit();
+			verification.verifying.shrink_to_fit();
+			verification.verified.shrink_to_fit();
+		}
+		self.processing.write().unwrap().shrink_to_fit();
+	}
 }

 impl MayPanic for BlockQueue {
@ -373,7 +425,7 @@ mod tests {
 	fn get_test_queue() -> BlockQueue {
 		let spec = get_test_spec();
 		let engine = spec.to_engine().unwrap();
-		BlockQueue::new(Arc::new(engine), IoChannel::disconnected())
+		BlockQueue::new(BlockQueueConfig::default(), Arc::new(engine), IoChannel::disconnected())
 	}

 	#[test]
@ -381,7 +433,7 @@ mod tests {
 		// TODO better test
 		let spec = Spec::new_test();
 		let engine = spec.to_engine().unwrap();
-		let _ = BlockQueue::new(Arc::new(engine), IoChannel::disconnected());
+		let _ = BlockQueue::new(BlockQueueConfig::default(), Arc::new(engine), IoChannel::disconnected());
 	}

 	#[test]
@ -437,4 +489,19 @@ mod tests {

 		assert!(queue.queue_info().is_empty());
 	}
+
+	#[test]
+	fn test_mem_limit() {
+		let spec = get_test_spec();
+		let engine = spec.to_engine().unwrap();
+		let mut config = BlockQueueConfig::default();
+		config.max_mem_use = super::MIN_MEM_LIMIT;  // empty queue uses about 15000
+		let mut queue = BlockQueue::new(config, Arc::new(engine), IoChannel::disconnected());
+		assert!(!queue.queue_info().is_full());
+		let mut blocks = get_good_dummy_block_seq(50);
+		for b in blocks.drain(..) {
+			queue.import_block(b).unwrap();
+		}
+		assert!(queue.queue_info().is_full());
+	}
 }
--- a/ethcore/src/blockchain.rs
+++ b/ethcore/src/blockchain.rs
@ -27,6 +27,24 @@ use chainfilter::{ChainFilter, BloomIndex, FilterDataSource};
 const BLOOM_INDEX_SIZE: usize = 16;
 const BLOOM_LEVELS: u8 = 3;

+/// Blockchain configuration.
+#[derive(Debug)]
+pub struct BlockChainConfig {
+	/// Preferred cache size in bytes.
+	pub pref_cache_size: usize,
+	/// Maximum cache size in bytes.
+	pub max_cache_size: usize,
+}
+
+impl Default for BlockChainConfig {
+	fn default() -> Self {
+		BlockChainConfig {
+			pref_cache_size: 1 << 14,
+			max_cache_size: 1 << 20,
+		}
+	}
+}
+
 /// Represents a tree route between `from` block and `to` block:
 pub struct TreeRoute {
 	/// A vector of hashes of all blocks, ordered from `from` to `to`.
@ -110,7 +128,7 @@ struct ExtrasUpdate {

 impl CacheSize {
 	/// Total amount used by the cache.
-	fn total(&self) -> usize { self.blocks + self.block_details + self.transaction_addresses + self.block_logs + self.blocks_blooms }
+	pub fn total(&self) -> usize { self.blocks + self.block_details + self.transaction_addresses + self.block_logs + self.blocks_blooms }
 }

 /// Information about best block gathered together
@ -308,33 +326,7 @@ const COLLECTION_QUEUE_SIZE: usize = 8;

 impl BlockChain {
 	/// Create new instance of blockchain from given Genesis
-	///
-	/// ```rust
-	/// extern crate ethcore_util as util;
-	/// extern crate ethcore;
-	/// use std::env;
-	/// use std::str::FromStr;
-	/// use ethcore::spec::*;
-	/// use ethcore::blockchain::*;
-	/// use ethcore::ethereum;
-	/// use util::hash::*;
-	/// use util::uint::*;
-	///
-	/// fn main() {
-	/// 	let spec = ethereum::new_frontier();
-	///
-	/// 	let mut dir = env::temp_dir();
-	/// 	dir.push(H32::random().hex());
-	///
-	/// 	let bc = BlockChain::new(&spec.genesis_block(), &dir);
-	///
-	/// 	let genesis_hash = "d4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3";
-	/// 	assert_eq!(bc.genesis_hash(), H256::from_str(genesis_hash).unwrap());
-	/// 	assert!(bc.is_known(&bc.genesis_hash()));
-	/// 	assert_eq!(bc.genesis_hash(), bc.block_hash(0).unwrap());
-	/// }
-	/// ```
-	pub fn new(genesis: &[u8], path: &Path) -> BlockChain {
+	pub fn new(config: BlockChainConfig, genesis: &[u8], path: &Path) -> BlockChain {
 		// open extras db
 		let mut extras_path = path.to_path_buf();
 		extras_path.push("extras");
@ -349,8 +341,8 @@ impl BlockChain {
 		(0..COLLECTION_QUEUE_SIZE).foreach(|_| cache_man.cache_usage.push_back(HashSet::new()));

 		let bc = BlockChain {
-			pref_cache_size: 1 << 14,
-			max_cache_size: 1 << 20,
+			pref_cache_size: config.pref_cache_size,
+			max_cache_size: config.max_cache_size,
 			best_block: RwLock::new(BestBlock::new()),
 			blocks: RwLock::new(HashMap::new()),
 			block_details: RwLock::new(HashMap::new()),
@ -813,7 +805,7 @@ mod tests {
 	use std::str::FromStr;
 	use rustc_serialize::hex::FromHex;
 	use util::hash::*;
-	use blockchain::{BlockProvider, BlockChain};
+	use blockchain::{BlockProvider, BlockChain, BlockChainConfig};
 	use tests::helpers::*;
 	use devtools::*;

@ -822,7 +814,7 @@ mod tests {
 		let genesis = "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".from_hex().unwrap();

 		let temp = RandomTempPath::new();
-		let bc = BlockChain::new(&genesis, temp.as_path());
+		let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());

 		let genesis_hash = H256::from_str("3caa2203f3d7c136c0295ed128a7d31cea520b1ca5e27afe17d0853331798942").unwrap();

@ -867,7 +859,7 @@ mod tests {
 		let best_block_hash = H256::from_str("c208f88c9f5bf7e00840439742c12e5226d9752981f3ec0521bdcb6dd08af277").unwrap();

 		let temp = RandomTempPath::new();
-		let bc = BlockChain::new(&genesis, temp.as_path());
+		let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());
 		bc.insert_block(&b1, vec![]);
 		bc.insert_block(&b2, vec![]);
 		bc.insert_block(&b3a, vec![]);
@ -946,14 +938,14 @@ mod tests {

 		let temp = RandomTempPath::new();
 		{
-			let bc = BlockChain::new(&genesis, temp.as_path());
+			let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());
 			assert_eq!(bc.best_block_hash(), genesis_hash);
 			bc.insert_block(&b1, vec![]);
 			assert_eq!(bc.best_block_hash(), b1_hash);
 		}

 		{
-			let bc = BlockChain::new(&genesis, temp.as_path());
+			let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());
 			assert_eq!(bc.best_block_hash(), b1_hash);
 		}
 	}
@ -1006,7 +998,7 @@ mod tests {
 		let b1_hash = H256::from_str("f53f268d23a71e85c7d6d83a9504298712b84c1a2ba220441c86eeda0bf0b6e3").unwrap();

 		let temp = RandomTempPath::new();
-		let bc = BlockChain::new(&genesis, temp.as_path());
+		let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());
 		bc.insert_block(&b1, vec![]);
 	
 		let transactions = bc.transactions(&b1_hash).unwrap();
@ -1042,7 +1034,7 @@ mod tests {
 		let bloom_ba = H2048::from_str("00000000000000000000000000000000000000000000020000000800000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000008000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000040000000000000000000000000000000000000000000000000000000000000000000000000000000000000000").unwrap();

 		let temp = RandomTempPath::new();
-		let bc = BlockChain::new(&genesis, temp.as_path());
+		let bc = BlockChain::new(BlockChainConfig::default(), &genesis, temp.as_path());

 		let blocks_b1 = bc.blocks_with_bloom(&bloom_b1, 0, 5);
 		let blocks_b2 = bc.blocks_with_bloom(&bloom_b2, 0, 5);
--- a/ethcore/src/client.rs
+++ b/ethcore/src/client.rs
@ -18,7 +18,7 @@

 use util::*;
 use util::panics::*;
-use blockchain::{BlockChain, BlockProvider, CacheSize};
+use blockchain::{BlockChain, BlockProvider};
 use views::BlockView;
 use error::*;
 use header::{BlockNumber, Header};
@ -26,7 +26,7 @@ use state::State;
 use spec::Spec;
 use engine::Engine;
 use views::HeaderView;
-use block_queue::{BlockQueue, BlockQueueInfo};
+use block_queue::BlockQueue;
 use service::{NetSyncMessage, SyncMessage};
 use env_info::LastHashes;
 use verification::*;
@ -35,7 +35,8 @@ use transaction::LocalizedTransaction;
 use extras::TransactionAddress;
 use filter::Filter;
 use log_entry::LocalizedLogEntry;
-pub use blockchain::TreeRoute;
+pub use block_queue::{BlockQueueConfig, BlockQueueInfo};
+pub use blockchain::{TreeRoute, BlockChainConfig, CacheSize as BlockChainCacheSize};

 /// Uniquely identifies block.
 #[derive(Debug, PartialEq, Clone)]
@ -74,7 +75,16 @@ pub enum BlockStatus {
 	Unknown,
 }

-/// Information about the blockchain gthered together.
+/// Client configuration. Includes configs for all sub-systems.
+#[derive(Debug, Default)]
+pub struct ClientConfig {
+	/// Block queue configuration.
+	pub queue: BlockQueueConfig,
+	/// Blockchain configuration.
+	pub blockchain: BlockChainConfig,
+}
+
+/// Information about the blockchain gathered together.
 #[derive(Debug)]
 pub struct BlockChainInfo {
 	/// Blockchain difficulty.
@ -190,14 +200,14 @@ const CLIENT_DB_VER_STR: &'static str = "4.0";

 impl Client {
 	/// Create a new client with given spec and DB path.
-	pub fn new(spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Arc<Client>, Error> {
+	pub fn new(config: ClientConfig, spec: Spec, path: &Path, message_channel: IoChannel<NetSyncMessage> ) -> Result<Arc<Client>, Error> {
 		let mut dir = path.to_path_buf();
 		dir.push(H64::from(spec.genesis_header().hash()).hex());
 		//TODO: sec/fat: pruned/full versioning
 		dir.push(format!("v{}-sec-pruned", CLIENT_DB_VER_STR));
 		let path = dir.as_path();
 		let gb = spec.genesis_block();
-		let chain = Arc::new(RwLock::new(BlockChain::new(&gb, path)));
+		let chain = Arc::new(RwLock::new(BlockChain::new(config.blockchain, &gb, path)));
 		let mut state_path = path.to_path_buf();
 		state_path.push("state");

@ -207,7 +217,7 @@ impl Client {
 			state_db.commit(0, &engine.spec().genesis_header().hash(), None).expect("Error commiting genesis state to state DB");
 		}

-		let block_queue = BlockQueue::new(engine.clone(), message_channel);
+		let block_queue = BlockQueue::new(config.queue, engine.clone(), message_channel);
 		let panic_handler = PanicHandler::new_in_arc();
 		panic_handler.forward_from(&block_queue);

@ -356,7 +366,7 @@ impl Client {
 	}

 	/// Get info on the cache.
-	pub fn cache_info(&self) -> CacheSize {
+	pub fn blockchain_cache_info(&self) -> BlockChainCacheSize {
 		self.chain.read().unwrap().cache_size()
 	}

@ -368,6 +378,7 @@ impl Client {
 	/// Tick the client.
 	pub fn tick(&self) {
 		self.chain.read().unwrap().collect_garbage();
+		self.block_queue.read().unwrap().collect_garbage();
 	}

 	/// Set up the cache behaviour.
--- a/ethcore/src/json_tests/chain.rs
+++ b/ethcore/src/json_tests/chain.rs
@ -15,7 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 use super::test_common::*;
-use client::{BlockChainClient,Client};
+use client::{BlockChainClient, Client, ClientConfig};
 use pod_state::*;
 use block::Block;
 use ethereum;
@ -53,7 +53,7 @@ pub fn json_chain_test(json_data: &[u8], era: ChainEra) -> Vec<String> {

 			let temp = RandomTempPath::new();
 			{
-				let client = Client::new(spec, temp.as_path(), IoChannel::disconnected()).unwrap();
+				let client = Client::new(ClientConfig::default(), spec, temp.as_path(), IoChannel::disconnected()).unwrap();
 				assert_eq!(client.chain_info().best_block_hash, genesis_hash);
 				for (b, is_valid) in blocks.into_iter() {
 					if Block::is_good(&b) {
--- a/ethcore/src/lib.rs
+++ b/ethcore/src/lib.rs
@ -75,7 +75,7 @@
 #[macro_use] extern crate ethcore_util as util;
 #[macro_use] extern crate lazy_static;
 extern crate rustc_serialize;
-extern crate heapsize;
+#[macro_use] extern crate heapsize;
 extern crate crypto;
 extern crate time;
 extern crate env_logger;
@ -86,8 +86,6 @@ extern crate crossbeam;
 #[cfg(feature = "jit" )] extern crate evmjit;

 pub mod block;
-pub mod blockchain;
-pub mod block_queue;
 pub mod client;
 pub mod error;
 pub mod ethereum;
@ -121,6 +119,8 @@ mod substate;
 mod executive;
 mod externalities;
 mod verification;
+mod block_queue;
+mod blockchain;

 #[cfg(test)]
 mod tests;
--- a/ethcore/src/service.rs
+++ b/ethcore/src/service.rs
@ -20,7 +20,7 @@ use util::*;
 use util::panics::*;
 use spec::Spec;
 use error::*;
-use client::Client;
+use client::{Client, ClientConfig};

 /// Message type for external and internal events
 #[derive(Clone)]
@ -48,14 +48,14 @@ pub struct ClientService {

 impl ClientService {
 	/// Start the service in a separate thread.
-	pub fn start(spec: Spec, net_config: NetworkConfiguration, db_path: &Path) -> Result<ClientService, Error> {
+	pub fn start(config: ClientConfig, spec: Spec, net_config: NetworkConfiguration, db_path: &Path) -> Result<ClientService, Error> {
 		let panic_handler = PanicHandler::new_in_arc();
 		let mut net_service = try!(NetworkService::start(net_config));
 		panic_handler.forward_from(&net_service);

 		info!("Starting {}", net_service.host_info());
 		info!("Configured for {} using {} engine", spec.name, spec.engine_name);
-		let client = try!(Client::new(spec, db_path, net_service.io().channel()));
+		let client = try!(Client::new(config, spec, db_path, net_service.io().channel()));
 		panic_handler.forward_from(client.deref());
 		let client_io = Arc::new(ClientIoHandler {
 			client: client.clone()
@ -135,12 +135,13 @@ mod tests {
 	use tests::helpers::*;
 	use util::network::*;
 	use devtools::*;
+	use client::ClientConfig;

 	#[test]
 	fn it_can_be_started() {
 		let spec = get_test_spec();
 		let temp_path = RandomTempPath::new();
-		let service = ClientService::start(spec, NetworkConfiguration::new_with_port(40456), &temp_path.as_path());
+		let service = ClientService::start(ClientConfig::default(), spec, NetworkConfiguration::new_with_port(40456), &temp_path.as_path());
 		assert!(service.is_ok());
 	}
 }
--- a/ethcore/src/spec.rs
+++ b/ethcore/src/spec.rs
@ -58,6 +58,8 @@ pub struct Spec {

 	/// Known nodes on the network in enode format.
 	pub nodes: Vec<String>,
+	/// Network ID
+	pub network_id: U256,

 	/// Parameters concerning operation of the specific engine we're using.
 	/// Maps the parameter name to an RLP-encoded value.
@ -120,6 +122,9 @@ impl Spec {
 	/// Get the known knodes of the network in enode format.
 	pub fn nodes(&self) -> &Vec<String> { &self.nodes }

+	/// Get the configured Network ID.
+	pub fn network_id(&self) -> U256 { self.network_id }
+
 	/// Get the header of the genesis block.
 	pub fn genesis_header(&self) -> Header {
 		Header {
@ -250,6 +255,7 @@ impl FromJson for Spec {
 			engine_name: json["engineName"].as_string().unwrap().to_owned(),
 			engine_params: json_to_rlp_map(&json["params"]),
 			nodes: nodes,
+			network_id: U256::from_str(&json["params"]["networkID"].as_string().unwrap()[2..]).unwrap(),
 			builtins: builtins,
 			parent_hash: H256::from_str(&genesis["parentHash"].as_string().unwrap()[2..]).unwrap(),
 			author: Address::from_str(&genesis["author"].as_string().unwrap()[2..]).unwrap(),
--- a/ethcore/src/tests/client.rs
+++ b/ethcore/src/tests/client.rs
@ -14,7 +14,7 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

-use client::{BlockChainClient, Client, BlockId};
+use client::{BlockChainClient, Client, ClientConfig, BlockId};
 use tests::helpers::*;
 use common::*;
 use devtools::*;
@ -22,14 +22,14 @@ use devtools::*;
 #[test]
 fn created() {
 	let dir = RandomTempPath::new();
-	let client_result = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected());
+	let client_result = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected());
 	assert!(client_result.is_ok());
 }

 #[test]
 fn imports_from_empty() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
 	client.import_verified_blocks(&IoChannel::disconnected());
 	client.flush_queue();
 }
@ -37,7 +37,7 @@ fn imports_from_empty() {
 #[test]
 fn imports_good_block() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
 	let good_block = get_good_dummy_block();
 	if let Err(_) = client.import_block(good_block) {
 		panic!("error importing block being good by definition");
@ -52,7 +52,7 @@ fn imports_good_block() {
 #[test]
 fn query_none_block() {
 	let dir = RandomTempPath::new();
-	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();

    let non_existant = client.block_header(BlockId::Number(188));
 	assert!(non_existant.is_none());
@ -104,5 +104,5 @@ fn can_collect_garbage() {
 	let client_result = generate_dummy_client(100);
 	let client = client_result.reference();
 	client.tick();
-	assert!(client.cache_info().blocks < 100 * 1024);
+	assert!(client.blockchain_cache_info().blocks < 100 * 1024);
 }
--- a/ethcore/src/tests/helpers.rs
+++ b/ethcore/src/tests/helpers.rs
@ -14,10 +14,10 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

-use client::{BlockChainClient, Client};
+use client::{BlockChainClient, Client, ClientConfig};
 use common::*;
 use spec::*;
-use blockchain::{BlockChain};
+use blockchain::{BlockChain, BlockChainConfig};
 use state::*;
 use evm::{Schedule, Factory};
 use engine::*;
@ -134,7 +134,7 @@ pub fn create_test_block_with_data(header: &Header, transactions: &[&SignedTrans
 pub fn generate_dummy_client(block_number: u32) -> GuardedTempResult<Arc<Client>> {
 	let dir = RandomTempPath::new();

-	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
 	let test_spec = get_test_spec();
 	let test_engine = test_spec.to_engine().unwrap();
 	let state_root = test_engine.spec().genesis_header().state_root;
@ -172,7 +172,7 @@ pub fn generate_dummy_client(block_number: u32) -> GuardedTempResult<Arc<Client>

 pub fn get_test_client_with_blocks(blocks: Vec<Bytes>) -> GuardedTempResult<Arc<Client>> {
 	let dir = RandomTempPath::new();
-	let client = Client::new(get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
+	let client = Client::new(ClientConfig::default(), get_test_spec(), dir.as_path(), IoChannel::disconnected()).unwrap();
 	for block in &blocks {
 		if let Err(_) = client.import_block(block.clone()) {
 			panic!("panic importing block which is well-formed");
@ -189,7 +189,7 @@ pub fn get_test_client_with_blocks(blocks: Vec<Bytes>) -> GuardedTempResult<Arc<

 pub fn generate_dummy_blockchain(block_number: u32) -> GuardedTempResult<BlockChain> {
 	let temp = RandomTempPath::new();
-	let bc = BlockChain::new(&create_unverifiable_block(0, H256::zero()), temp.as_path());
+	let bc = BlockChain::new(BlockChainConfig::default(), &create_unverifiable_block(0, H256::zero()), temp.as_path());
 	for block_order in 1..block_number {
 		bc.insert_block(&create_unverifiable_block(block_order, bc.best_block_hash()), vec![]);
 	}
@ -202,7 +202,7 @@ pub fn generate_dummy_blockchain(block_number: u32) -> GuardedTempResult<BlockCh

 pub fn generate_dummy_blockchain_with_extra(block_number: u32) -> GuardedTempResult<BlockChain> {
 	let temp = RandomTempPath::new();
-	let bc = BlockChain::new(&create_unverifiable_block(0, H256::zero()), temp.as_path());
+	let bc = BlockChain::new(BlockChainConfig::default(), &create_unverifiable_block(0, H256::zero()), temp.as_path());
 	for block_order in 1..block_number {
 		bc.insert_block(&create_unverifiable_block_with_extra(block_order, bc.best_block_hash(), None), vec![]);
 	}
@ -215,7 +215,7 @@ pub fn generate_dummy_blockchain_with_extra(block_number: u32) -> GuardedTempRes

 pub fn generate_dummy_empty_blockchain() -> GuardedTempResult<BlockChain> {
 	let temp = RandomTempPath::new();
-	let bc = BlockChain::new(&create_unverifiable_block(0, H256::zero()), temp.as_path());
+	let bc = BlockChain::new(BlockChainConfig::default(), &create_unverifiable_block(0, H256::zero()), temp.as_path());

 	GuardedTempResult::<BlockChain> {
 		_temp: temp,
@ -250,6 +250,25 @@ pub fn get_temp_state_in(path: &Path) -> State {
 	State::new(journal_db, U256::from(0u8))
 }

+pub fn get_good_dummy_block_seq(count: usize) -> Vec<Bytes> {
+	let test_spec = get_test_spec();
+	let test_engine = test_spec.to_engine().unwrap();
+	let mut parent = test_engine.spec().genesis_header().hash();
+	let mut r = Vec::new();
+	for i in 1 .. count + 1 {
+		let mut block_header = Header::new();
+		block_header.gas_limit = decode(test_engine.spec().engine_params.get("minGasLimit").unwrap());
+		block_header.difficulty = decode(test_engine.spec().engine_params.get("minimumDifficulty").unwrap());
+		block_header.timestamp = i as u64;
+		block_header.number = i as u64;
+		block_header.parent_hash = parent;
+		block_header.state_root = test_engine.spec().genesis_header().state_root;
+		parent = block_header.hash();
+		r.push(create_test_block(&block_header));
+	}
+	r
+}
+
 pub fn get_good_dummy_block() -> Bytes {
 	let mut block_header = Header::new();
 	let test_spec = get_test_spec();
--- a/parity/main.rs
+++ b/parity/main.rs
@ -31,6 +31,7 @@ extern crate ctrlc;
 extern crate fdlimit;
 extern crate daemonize;
 extern crate time;
+extern crate number_prefix;

 #[cfg(feature = "rpc")]
 extern crate ethcore_rpc as rpc;
@ -47,10 +48,10 @@ use ethcore::spec::*;
 use ethcore::client::*;
 use ethcore::service::{ClientService, NetSyncMessage};
 use ethcore::ethereum;
-use ethcore::blockchain::CacheSize;
-use ethsync::EthSync;
+use ethsync::{EthSync, SyncConfig};
 use docopt::Docopt;
 use daemonize::Daemonize;
+use number_prefix::{binary_prefix, Standalone, Prefixed};

 const USAGE: &'static str = r#"
 Parity. Ethereum Client.
@ -78,6 +79,7 @@ Options:

  --cache-pref-size BYTES  Specify the prefered size of the blockchain cache in bytes [default: 16384].
  --cache-max-size BYTES   Specify the maximum size of the blockchain cache in bytes [default: 262144].
+  --queue-max-size BYTES   Specify the maximum size of memory to use for block queue [default: 52428800].

  -j --jsonrpc             Enable the JSON-RPC API sever.
  --jsonrpc-url URL        Specify URL for JSON-RPC API server [default: 127.0.0.1:8545].
@ -106,6 +108,7 @@ struct Args {
 	flag_node_key: Option<String>,
 	flag_cache_pref_size: usize,
 	flag_cache_max_size: usize,
+	flag_queue_max_size: usize,
 	flag_jsonrpc: bool,
 	flag_jsonrpc_url: String,
 	flag_jsonrpc_cors: String,
@ -283,14 +286,19 @@ impl Configuration {

 		let spec = self.spec();
 		let net_settings = self.net_settings(&spec);
+		let mut sync_config = SyncConfig::default();
+		sync_config.network_id = spec.network_id();

 		// Build client
-		let mut service = ClientService::start(spec, net_settings, &Path::new(&self.path())).unwrap();
+		let mut client_config = ClientConfig::default();
+		client_config.blockchain.pref_cache_size = self.args.flag_cache_pref_size;
+		client_config.blockchain.max_cache_size = self.args.flag_cache_max_size;
+		client_config.queue.max_mem_use = self.args.flag_queue_max_size;
+		let mut service = ClientService::start(client_config, spec, net_settings, &Path::new(&self.path())).unwrap();
 		let client = service.client().clone();
-		client.configure_cache(self.args.flag_cache_pref_size, self.args.flag_cache_max_size);

 		// Sync
-		let sync = EthSync::register(service.network(), client);
+		let sync = EthSync::register(service.network(), sync_config, client);

 		// Setup rpc
 		if self.args.flag_jsonrpc {
@ -331,7 +339,7 @@ fn main() {

 struct Informant {
 	chain_info: RwLock<Option<BlockChainInfo>>,
-	cache_info: RwLock<Option<CacheSize>>,
+	cache_info: RwLock<Option<BlockChainCacheSize>>,
 	report: RwLock<Option<ClientReport>>,
 }

@ -346,18 +354,26 @@ impl Default for Informant {
 }

 impl Informant {
+
+	fn format_bytes(b: usize) -> String {
+		match binary_prefix(b as f64) {
+			Standalone(bytes)   => format!("{} bytes", bytes),
+			Prefixed(prefix, n) => format!("{:.0} {}B", n, prefix),
+		}
+	}
+
 	pub fn tick(&self, client: &Client, sync: &EthSync) {
 		// 5 seconds betwen calls. TODO: calculate this properly.
 		let dur = 5usize;

 		let chain_info = client.chain_info();
 		let queue_info = client.queue_info();
-		let cache_info = client.cache_info();
+		let cache_info = client.blockchain_cache_info();
 		let report = client.report();
 		let sync_info = sync.status();

-		if let (_, &Some(ref last_cache_info), &Some(ref last_report)) = (self.chain_info.read().unwrap().deref(), self.cache_info.read().unwrap().deref(), self.report.read().unwrap().deref()) {
-			println!("[ #{} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //··· {}/{} peers, #{}, {}+{} queued ···//  {} ({}) bl  {} ({}) ex ]",
+		if let (_, _, &Some(ref last_report)) = (self.chain_info.read().unwrap().deref(), self.cache_info.read().unwrap().deref(), self.report.read().unwrap().deref()) {
+			println!("[ #{} {} ]---[ {} blk/s | {} tx/s | {} gas/s  //··· {}/{} peers, #{}, {}+{} queued ···// mem: {} chain, {} queue, {} sync ]",
 				chain_info.best_block_number,
 				chain_info.best_block_hash,
 				(report.blocks_imported - last_report.blocks_imported) / dur,
@ -370,10 +386,9 @@ impl Informant {
 				queue_info.unverified_queue_size,
 				queue_info.verified_queue_size,

-				cache_info.blocks,
-				cache_info.blocks as isize - last_cache_info.blocks as isize,
-				cache_info.block_details,
-				cache_info.block_details as isize - last_cache_info.block_details as isize
+				Informant::format_bytes(cache_info.total()),
+				Informant::format_bytes(queue_info.mem_used),
+				Informant::format_bytes(sync_info.mem_used),
 			);
 		}

--- a/sync/Cargo.toml
+++ b/sync/Cargo.toml
@ -15,6 +15,7 @@ log = "0.3"
 env_logger = "0.3"
 time = "0.1.34"
 rand = "0.3.13"
+heapsize = "0.3"

 [features]
 default = []
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@ -39,7 +39,9 @@ use ethcore::error::*;
 use ethcore::block::Block;
 use io::SyncIo;
 use time;
-use std::option::Option;
+use super::SyncConfig;
+
+known_heap_size!(0, PeerInfo, Header, HeaderId);

 impl ToUsize for BlockNumber {
 	fn to_usize(&self) -> usize {
@ -80,9 +82,7 @@ const NODE_DATA_PACKET: u8 = 0x0e;
 const GET_RECEIPTS_PACKET: u8 = 0x0f;
 const RECEIPTS_PACKET: u8 = 0x10;

-const NETWORK_ID: U256 = ONE_U256; //TODO: get this from parent
-
-const CONNECTION_TIMEOUT_SEC: f64 = 10f64;
+const CONNECTION_TIMEOUT_SEC: f64 = 5f64;

 struct Header {
 	/// Header data
@ -135,6 +135,8 @@ pub struct SyncStatus {
 	pub num_peers: usize,
 	/// Total number of active peers
 	pub num_active_peers: usize,
+	/// Heap memory used in bytes
+	pub mem_used: usize,
 }

 #[derive(PartialEq, Eq, Debug, Clone)]
@ -203,13 +205,17 @@ pub struct ChainSync {
 	have_common_block: bool,
 	/// Last propagated block number
 	last_send_block_number: BlockNumber,
+	/// Max blocks to download ahead
+	max_download_ahead_blocks: usize,
+	/// Network ID
+	network_id: U256,
 }

 type RlpResponseResult = Result<Option<(PacketId, RlpStream)>, PacketDecodeError>;

 impl ChainSync {
 	/// Create a new instance of syncing strategy.
-	pub fn new() -> ChainSync {
+	pub fn new(config: SyncConfig) -> ChainSync {
 		ChainSync {
 			state: SyncState::NotSynced,
 			starting_block: 0,
@ -226,6 +232,8 @@ impl ChainSync {
 			syncing_difficulty: U256::from(0u64),
 			have_common_block: false,
 			last_send_block_number: 0,
+			max_download_ahead_blocks: max(MAX_HEADERS_TO_REQUEST, config.max_download_ahead_blocks),
+			network_id: config.network_id,
 		}
 	}

@ -241,6 +249,15 @@ impl ChainSync {
 			blocks_total: match self.highest_block { None => 0, Some(x) => x - self.starting_block },
 			num_peers: self.peers.len(),
 			num_active_peers: self.peers.values().filter(|p| p.asking != PeerAsking::Nothing).count(),
+			mem_used: 
+				//  TODO: https://github.com/servo/heapsize/pull/50
+				//  self.downloading_hashes.heap_size_of_children() 
+				//+ self.downloading_bodies.heap_size_of_children() 
+				//+ self.downloading_hashes.heap_size_of_children() 
+				self.headers.heap_size_of_children() 
+				+ self.bodies.heap_size_of_children() 
+				+ self.peers.heap_size_of_children() 
+				+ self.header_ids.heap_size_of_children(),
 		}
 	}

@ -275,7 +292,6 @@ impl ChainSync {
 		self.starting_block = 0;
 		self.highest_block = None;
 		self.have_common_block = false;
-		io.chain().clear_queue();
 		self.starting_block = io.chain().chain_info().best_block_number;
 		self.state = SyncState::NotSynced;
 	}
@ -307,7 +323,7 @@ impl ChainSync {
 			trace!(target: "sync", "Peer {} genesis hash not matched", peer_id);
 			return Ok(());
 		}
-		if peer.network_id != NETWORK_ID {
+		if peer.network_id != self.network_id {
 			io.disable_peer(peer_id);
 			trace!(target: "sync", "Peer {} network id not matched", peer_id);
 			return Ok(());
@ -436,7 +452,7 @@ impl ChainSync {
 					trace!(target: "sync", "Got body {}", n);
 				}
 				None =>  {
-					debug!(target: "sync", "Ignored unknown block body");
+					trace!(target: "sync", "Ignored unknown/stale block body");
 				}
 			}
 		}
@ -611,7 +627,7 @@ impl ChainSync {
 			self.request_headers_by_hash(io, peer_id, &peer_latest, 1, 0, false);
 		}
 		else if self.state == SyncState::Blocks && io.chain().block_status(BlockId::Hash(peer_latest)) == BlockStatus::Unknown {
-			self.request_blocks(io, peer_id);
+			self.request_blocks(io, peer_id, false);
 		}
 	}

@ -620,7 +636,7 @@ impl ChainSync {
 	}

 	/// Find some headers or blocks to download for a peer.
-	fn request_blocks(&mut self, io: &mut SyncIo, peer_id: PeerId) {
+	fn request_blocks(&mut self, io: &mut SyncIo, peer_id: PeerId, ignore_others: bool) {
 		self.clear_peer_download(peer_id);

 		if io.chain().queue_info().is_full() {
@ -640,28 +656,34 @@ impl ChainSync {
 				let mut index: BlockNumber = 0;
 				while index != items.len() as BlockNumber && needed_bodies.len() < MAX_BODIES_TO_REQUEST {
 					let block = start + index;
-					if !self.downloading_bodies.contains(&block) && !self.bodies.have_item(&block) {
+					if  ignore_others || (!self.downloading_bodies.contains(&block) && !self.bodies.have_item(&block)) {
 						needed_bodies.push(items[index as usize].hash.clone());
 						needed_numbers.push(block);
-						self.downloading_bodies.insert(block);
 					}
 					index += 1;
 				}
 			}
 		}
 		if !needed_bodies.is_empty() {
+			let (head, _) = self.headers.range_iter().next().unwrap();
+			if needed_numbers.first().unwrap() - head > self.max_download_ahead_blocks as BlockNumber {
+				trace!(target: "sync", "{}: Stalled download ({} vs {}), helping with downloading block bodies", peer_id, needed_numbers.first().unwrap(), head);
+				self.request_blocks(io, peer_id, true);
+				return;
+			}
+			self.downloading_bodies.extend(needed_numbers.iter());
 			replace(&mut self.peers.get_mut(&peer_id).unwrap().asking_blocks, needed_numbers);
 			self.request_bodies(io, peer_id, needed_bodies);
 		}
 		else {
 			// check if need to download headers
-			let mut start = 0usize;
+			let mut start = 0;
 			if !self.have_common_block {
 				// download backwards until common block is found 1 header at a time
 				let chain_info = io.chain().chain_info();
-				start = chain_info.best_block_number as usize;
+				start = chain_info.best_block_number;
 				if !self.headers.is_empty() {
-					start = min(start, self.headers.range_iter().next().unwrap().0 as usize - 1);
+					start = min(start, self.headers.range_iter().next().unwrap().0 - 1);
 				}
 				if start == 0 {
 					self.have_common_block = true; //reached genesis
@ -672,6 +694,7 @@ impl ChainSync {
 			if self.have_common_block {
 				let mut headers: Vec<BlockNumber> = Vec::new();
 				let mut prev = self.current_base_block() + 1;
+				let head = self.headers.range_iter().next().map(|(h, _)| h);
 				for (next, ref items) in self.headers.range_iter() {
 					if !headers.is_empty() {
 						break;
@ -682,9 +705,8 @@ impl ChainSync {
 					}
 					let mut block = prev;
 					while block < next && headers.len() < MAX_HEADERS_TO_REQUEST {
-						if !self.downloading_headers.contains(&(block as BlockNumber)) {
+						if ignore_others || !self.downloading_headers.contains(&(block as BlockNumber)) {
 							headers.push(block as BlockNumber);
-							self.downloading_headers.insert(block as BlockNumber);
 						}
 						block += 1;
 					}
@ -692,17 +714,23 @@ impl ChainSync {
 				}

 				if !headers.is_empty() {
-					start = headers[0] as usize;
+					start = headers[0];
+					if head.is_some() && start > head.unwrap() && start - head.unwrap() > self.max_download_ahead_blocks as BlockNumber {
+						trace!(target: "sync", "{}: Stalled download ({} vs {}), helping with downloading headers", peer_id, start, head.unwrap());
+						self.request_blocks(io, peer_id, true);
+						return;
+					}
 					let count = headers.len();
+					self.downloading_headers.extend(headers.iter());
 					replace(&mut self.peers.get_mut(&peer_id).unwrap().asking_blocks, headers);
-					assert!(!self.headers.have_item(&(start as BlockNumber)));
-					self.request_headers_by_number(io, peer_id, start as BlockNumber, count, 0, false);
+					assert!(!self.headers.have_item(&start));
+					self.request_headers_by_number(io, peer_id, start, count, 0, false);
 				}
 			}
 			else {
 				// continue search for common block
-				self.downloading_headers.insert(start as BlockNumber);
-				self.request_headers_by_number(io, peer_id, start as BlockNumber, 1, 0, false);
+				self.downloading_headers.insert(start);
+				self.request_headers_by_number(io, peer_id, start, 1, 0, false);
 			}
 		}
 	}
@ -894,7 +922,7 @@ impl ChainSync {
 		let mut packet = RlpStream::new_list(5);
 		let chain = io.chain().chain_info();
 		packet.append(&(PROTOCOL_VERSION as u32));
-		packet.append(&NETWORK_ID); //TODO: network id
+		packet.append(&self.network_id);
 		packet.append(&chain.total_difficulty);
 		packet.append(&chain.best_block_hash);
 		packet.append(&chain.genesis_hash);
@ -1220,6 +1248,7 @@ impl ChainSync {
 mod tests {
 	use tests::helpers::*;
 	use super::*;
+	use ::SyncConfig;
 	use util::*;
 	use super::{PeerInfo, PeerAsking};
 	use ethcore::header::*;
@ -1333,7 +1362,7 @@ mod tests {
 	}

 	fn dummy_sync_with_peer(peer_latest_hash: H256) -> ChainSync {
-		let mut sync = ChainSync::new();
+		let mut sync = ChainSync::new(SyncConfig::default());
 		sync.peers.insert(0,
 		  	PeerInfo {
 				protocol_version: 0,
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@ -34,15 +34,15 @@
 //! use std::env;
 //! use std::sync::Arc;
 //! use util::network::{NetworkService, NetworkConfiguration};
-//! use ethcore::client::Client;
-//! use ethsync::EthSync;
+//! use ethcore::client::{Client, ClientConfig};
+//! use ethsync::{EthSync, SyncConfig};
 //! use ethcore::ethereum;
 //!
 //! fn main() {
 //! 	let mut service = NetworkService::start(NetworkConfiguration::new()).unwrap();
 //! 	let dir = env::temp_dir();
-//! 	let client = Client::new(ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
-//! 	EthSync::register(&mut service, client);
+//! 	let client = Client::new(ClientConfig::default(), ethereum::new_frontier(), &dir, service.io().channel()).unwrap();
+//! 	EthSync::register(&mut service, SyncConfig::default(), client);
 //! }
 //! ```

@ -54,12 +54,15 @@ extern crate ethcore;
 extern crate env_logger;
 extern crate time;
 extern crate rand;
+#[macro_use]
+extern crate heapsize;

 use std::ops::*;
 use std::sync::*;
 use ethcore::client::Client;
 use util::network::{NetworkProtocolHandler, NetworkService, NetworkContext, PeerId};
 use util::TimerToken;
+use util::{U256, ONE_U256};
 use chain::ChainSync;
 use ethcore::service::SyncMessage;
 use io::NetSyncIo;
@ -71,6 +74,23 @@ mod range_collection;
 #[cfg(test)]
 mod tests;

+/// Sync configuration
+pub struct SyncConfig {
+	/// Max blocks to download ahead
+	pub max_download_ahead_blocks: usize,
+	/// Network ID
+	pub network_id: U256,
+}
+
+impl Default for SyncConfig {
+	fn default() -> SyncConfig {
+		SyncConfig {
+			max_download_ahead_blocks: 20000,
+			network_id: ONE_U256,
+		}
+	}
+}
+
 /// Ethereum network protocol handler
 pub struct EthSync {
 	/// Shared blockchain client. TODO: this should evetually become an IPC endpoint
@ -83,10 +103,10 @@ pub use self::chain::{SyncStatus, SyncState};

 impl EthSync {
 	/// Creates and register protocol with the network service
-	pub fn register(service: &mut NetworkService<SyncMessage>, chain: Arc<Client>) -> Arc<EthSync> {
+	pub fn register(service: &mut NetworkService<SyncMessage>, config: SyncConfig, chain: Arc<Client>) -> Arc<EthSync> {
 		let sync = Arc::new(EthSync {
 			chain: chain,
-			sync: RwLock::new(ChainSync::new()),
+			sync: RwLock::new(ChainSync::new(config)),
 		});
 		service.register_protocol(sync.clone(), "eth", &[62u8, 63u8]).expect("Error registering eth protocol handler");
 		sync
--- a/sync/src/tests/helpers.rs
+++ b/sync/src/tests/helpers.rs
@ -15,12 +15,12 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.

 use util::*;
-use ethcore::client::{BlockChainClient, BlockStatus, TreeRoute, BlockChainInfo, TransactionId, BlockId};
-use ethcore::block_queue::BlockQueueInfo;
+use ethcore::client::{BlockChainClient, BlockStatus, TreeRoute, BlockChainInfo, TransactionId, BlockId, BlockQueueInfo};
 use ethcore::header::{Header as BlockHeader, BlockNumber};
 use ethcore::error::*;
 use io::SyncIo;
-use chain::{ChainSync};
+use chain::ChainSync;
+use ::SyncConfig;
 use ethcore::receipt::Receipt;
 use ethcore::transaction::LocalizedTransaction;
 use ethcore::filter::Filter;
@ -251,6 +251,9 @@ impl BlockChainClient for TestBlockChainClient {
 			verified_queue_size: 0,
 			unverified_queue_size: 0,
 			verifying_queue_size: 0,
+			max_queue_size: 0,
+			max_mem_use: 0,
+			mem_used: 0,
 		}
 	}

@ -340,7 +343,7 @@ impl TestNet {
 		for _ in 0..n {
 			net.peers.push(TestPeer {
 				chain: TestBlockChainClient::new(),
-				sync: ChainSync::new(),
+				sync: ChainSync::new(SyncConfig::default()),
 				queue: VecDeque::new(),
 			});
 		}