From d8e703c4b863b150b47ff16ed4dae762925005c4 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Sun, 21 Jun 2020 14:30:56 +0200
Subject: [PATCH 1/8] Fix typo in offchain's docs

---
 client/offchain/src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/client/offchain/src/lib.rs b/client/offchain/src/lib.rs
index a1ea16a72e9f4..7377da2cdb0b7 100644
--- a/client/offchain/src/lib.rs
+++ b/client/offchain/src/lib.rs
@@ -19,7 +19,7 @@
 //! The offchain workers is a special function of the runtime that
 //! gets executed after block is imported. During execution
 //! it's able to asynchronously submit extrinsics that will either
-//! be propagated to other nodes added to the next block
+//! be propagated to other nodes or added to the next block
 //! produced by the node as unsigned transactions.
 //!
 //! Offchain workers can be used for computation-heavy tasks

From c23b583bf2e50366efb61618fea0b24ca5ba17ba Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Sun, 21 Jun 2020 15:29:22 +0200
Subject: [PATCH 2/8] Use Self keyword in AsyncApi::new()

---
 client/offchain/src/api.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/client/offchain/src/api.rs b/client/offchain/src/api.rs
index a7f4ecbc5825e..d84c869c9bed8 100644
--- a/client/offchain/src/api.rs
+++ b/client/offchain/src/api.rs
@@ -260,7 +260,7 @@ impl AsyncApi {
 		db: S,
 		network_state: Arc<dyn NetworkStateInfo + Send + Sync>,
 		is_validator: bool,
-	) -> (Api<S>, AsyncApi) {
+	) -> (Api<S>, Self) {
 		let (http_api, http_worker) = http::http();
 
 		let api = Api {
@@ -270,7 +270,7 @@ impl AsyncApi {
 			http: http_api,
 		};
 
-		let async_api = AsyncApi {
+		let async_api = Self {
 			http: Some(http_worker),
 		};
 

From d8fbf03ae1f5fdf56d6e50774d3a46603504dcd5 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Sun, 21 Jun 2020 16:19:59 +0200
Subject: [PATCH 3/8] Move httpclient to be part of OffchainWorkers to optimize
 block import

---
 client/offchain/src/api.rs      | 3 ++-
 client/offchain/src/api/http.rs | 9 ++++++---
 client/offchain/src/lib.rs      | 6 ++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/client/offchain/src/api.rs b/client/offchain/src/api.rs
index d84c869c9bed8..85d31b3482022 100644
--- a/client/offchain/src/api.rs
+++ b/client/offchain/src/api.rs
@@ -260,8 +260,9 @@ impl AsyncApi {
 		db: S,
 		network_state: Arc<dyn NetworkStateInfo + Send + Sync>,
 		is_validator: bool,
+		hyper_client: Arc<hyper::Client<hyper_rustls::HttpsConnector<hyper::client::HttpConnector>, hyper::Body>>,
 	) -> (Api<S>, Self) {
-		let (http_api, http_worker) = http::http();
+		let (http_api, http_worker) = http::http(hyper_client);
 
 		let api = Api {
 			db,
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index 91a673872fc7c..e71296e15dd62 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -33,9 +33,12 @@ use log::error;
 use sp_core::offchain::{HttpRequestId, Timestamp, HttpRequestStatus, HttpError};
 use std::{convert::TryFrom, fmt, io::Read as _, pin::Pin, task::{Context, Poll}};
 use sp_utils::mpsc::{tracing_unbounded, TracingUnboundedSender, TracingUnboundedReceiver};
+use std::sync::Arc;
+use hyper::{Client, Body, client};
+use hyper_rustls::HttpsConnector;
 
 /// Creates a pair of [`HttpApi`] and [`HttpWorker`].
-pub fn http() -> (HttpApi, HttpWorker) {
+pub fn http(hyper_client: Arc<Client<HttpsConnector<client::HttpConnector>, Body>>) -> (HttpApi, HttpWorker) {
 	let (to_worker, from_api) = tracing_unbounded("mpsc_ocw_to_worker");
 	let (to_api, from_worker) = tracing_unbounded("mpsc_ocw_to_api");
 
@@ -51,7 +54,7 @@ pub fn http() -> (HttpApi, HttpWorker) {
 	let engine = HttpWorker {
 		to_api,
 		from_api,
-		http_client: hyper::Client::builder().build(hyper_rustls::HttpsConnector::new()),
+		http_client: hyper_client,
 		requests: Vec::new(),
 	};
 
@@ -551,7 +554,7 @@ pub struct HttpWorker {
 	/// Used to receive messages from the `HttpApi`.
 	from_api: TracingUnboundedReceiver<ApiToWorker>,
 	/// The engine that runs HTTP requests.
-	http_client: hyper::Client<hyper_rustls::HttpsConnector<hyper::client::HttpConnector>, hyper::Body>,
+	http_client: Arc<Client<HttpsConnector<client::HttpConnector>, Body>>,
 	/// HTTP requests that are being worked on by the engine.
 	requests: Vec<(HttpRequestId, HttpWorkerRequest)>,
 }
diff --git a/client/offchain/src/lib.rs b/client/offchain/src/lib.rs
index 7377da2cdb0b7..2562620fefa1f 100644
--- a/client/offchain/src/lib.rs
+++ b/client/offchain/src/lib.rs
@@ -44,6 +44,8 @@ use sc_network::NetworkStateInfo;
 use sp_core::{offchain::{self, OffchainStorage}, ExecutionContext, traits::SpawnNamed};
 use sp_runtime::{generic::BlockId, traits::{self, Header}};
 use futures::{prelude::*, future::ready};
+use hyper_rustls::HttpsConnector;
+use hyper::{Client as HyperClient, Body, client};
 
 mod api;
 
@@ -55,16 +57,19 @@ pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 	db: Storage,
 	_block: PhantomData<Block>,
 	thread_pool: Mutex<ThreadPool>,
+	hyper_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>,
 }
 
 impl<Client, Storage, Block: traits::Block> OffchainWorkers<Client, Storage, Block> {
 	/// Creates new `OffchainWorkers`.
 	pub fn new(client: Arc<Client>, db: Storage) -> Self {
+		let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
 		Self {
 			client,
 			db,
 			_block: PhantomData,
 			thread_pool: Mutex::new(ThreadPool::new(num_cpus::get())),
+			hyper_client,
 		}
 	}
 }
@@ -120,6 +125,7 @@ impl<Client, Storage, Block> OffchainWorkers<
 				self.db.clone(),
 				network_state.clone(),
 				is_validator,
+				self.hyper_client.clone(),
 			);
 			debug!("Spawning offchain workers at {:?}", at);
 			let header = header.clone();

From 814c48132dee9c34de2f9e29c96b93e84f0407a2 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Sun, 21 Jun 2020 17:27:55 +0200
Subject: [PATCH 4/8] Fix compilation errors for tests

---
 client/offchain/src/api.rs      |  5 +++++
 client/offchain/src/api/http.rs | 12 ++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/client/offchain/src/api.rs b/client/offchain/src/api.rs
index 85d31b3482022..bd1fcbf88efcd 100644
--- a/client/offchain/src/api.rs
+++ b/client/offchain/src/api.rs
@@ -292,6 +292,8 @@ mod tests {
 	use std::{convert::{TryFrom, TryInto}, time::SystemTime};
 	use sc_client_db::offchain::LocalStorage;
 	use sc_network::PeerId;
+	use hyper_rustls::HttpsConnector;
+	use hyper::{Client as HyperClient};
 
 	struct MockNetworkStateInfo();
 
@@ -309,11 +311,14 @@ mod tests {
 		let _ = env_logger::try_init();
 		let db = LocalStorage::new_test();
 		let mock = Arc::new(MockNetworkStateInfo());
+		let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
+
 
 		AsyncApi::new(
 			db,
 			mock,
 			false,
+			hyper_client,
 		)
 	}
 
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index e71296e15dd62..89be2aefc8299 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -34,11 +34,11 @@ use sp_core::offchain::{HttpRequestId, Timestamp, HttpRequestStatus, HttpError};
 use std::{convert::TryFrom, fmt, io::Read as _, pin::Pin, task::{Context, Poll}};
 use sp_utils::mpsc::{tracing_unbounded, TracingUnboundedSender, TracingUnboundedReceiver};
 use std::sync::Arc;
-use hyper::{Client, Body, client};
+use hyper::{Client as HyperClient, Body, client};
 use hyper_rustls::HttpsConnector;
 
 /// Creates a pair of [`HttpApi`] and [`HttpWorker`].
-pub fn http(hyper_client: Arc<Client<HttpsConnector<client::HttpConnector>, Body>>) -> (HttpApi, HttpWorker) {
+pub fn http(hyper_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>) -> (HttpApi, HttpWorker) {
 	let (to_worker, from_api) = tracing_unbounded("mpsc_ocw_to_worker");
 	let (to_api, from_worker) = tracing_unbounded("mpsc_ocw_to_api");
 
@@ -554,7 +554,7 @@ pub struct HttpWorker {
 	/// Used to receive messages from the `HttpApi`.
 	from_api: TracingUnboundedReceiver<ApiToWorker>,
 	/// The engine that runs HTTP requests.
-	http_client: Arc<Client<HttpsConnector<client::HttpConnector>, Body>>,
+	http_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>,
 	/// HTTP requests that are being worked on by the engine.
 	requests: Vec<(HttpRequestId, HttpWorkerRequest)>,
 }
@@ -691,6 +691,9 @@ mod tests {
 	use super::http;
 	use sp_core::offchain::{HttpError, HttpRequestId, HttpRequestStatus, Duration};
 	use futures::future;
+	use std::sync::Arc;
+	use hyper::{Client as HyperClient};
+	use hyper_rustls::HttpsConnector;
 
 	// Returns an `HttpApi` whose worker is ran in the background, and a `SocketAddr` to an HTTP
 	// server that runs in the background as well.
@@ -702,7 +705,8 @@ mod tests {
 			// not be enough).
 			fdlimit::raise_fd_limit();
 
-			let (api, worker) = http();
+			let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
+			let (api, worker) = http(hyper_client.clone());
 
 			let (addr_tx, addr_rx) = std::sync::mpsc::channel();
 			std::thread::spawn(move || {

From cf434c811262004efbf91c1510b12021e70071f7 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Mon, 22 Jun 2020 16:29:17 +0200
Subject: [PATCH 5/8] Add wrapper struct for HyperClient

---
 client/offchain/src/api.rs            |  3 ++-
 client/offchain/src/api/http.rs       | 14 ++++++++++++--
 client/offchain/src/api/http_dummy.rs | 12 +++++++++++-
 client/offchain/src/lib.rs            | 11 +++++------
 4 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/client/offchain/src/api.rs b/client/offchain/src/api.rs
index bd1fcbf88efcd..b4c414eb4748e 100644
--- a/client/offchain/src/api.rs
+++ b/client/offchain/src/api.rs
@@ -31,6 +31,7 @@ use sp_core::offchain::{
 	OpaqueNetworkState, OpaquePeerId, OpaqueMultiaddr, StorageKind,
 };
 pub use sp_offchain::STORAGE_PREFIX;
+pub use http::SharedClient;
 
 #[cfg(not(target_os = "unknown"))]
 mod http;
@@ -260,7 +261,7 @@ impl AsyncApi {
 		db: S,
 		network_state: Arc<dyn NetworkStateInfo + Send + Sync>,
 		is_validator: bool,
-		hyper_client: Arc<hyper::Client<hyper_rustls::HttpsConnector<hyper::client::HttpConnector>, hyper::Body>>,
+		hyper_client: SharedClient,
 	) -> (Api<S>, Self) {
 		let (http_api, http_worker) = http::http(hyper_client);
 
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index 89be2aefc8299..7860a95c2142a 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -37,8 +37,18 @@ use std::sync::Arc;
 use hyper::{Client as HyperClient, Body, client};
 use hyper_rustls::HttpsConnector;
 
+/// Wrapper struct used for keeping the hyper_rustls client running.
+#[derive(Clone)]
+pub struct SharedClient(Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>);
+
+impl SharedClient {
+	pub fn new() -> Self {
+		Self(Arc::new(HyperClient::builder().build(HttpsConnector::new())))
+	}
+}
+
 /// Creates a pair of [`HttpApi`] and [`HttpWorker`].
-pub fn http(hyper_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>) -> (HttpApi, HttpWorker) {
+pub fn http(shared_client: SharedClient) -> (HttpApi, HttpWorker) {
 	let (to_worker, from_api) = tracing_unbounded("mpsc_ocw_to_worker");
 	let (to_api, from_worker) = tracing_unbounded("mpsc_ocw_to_api");
 
@@ -54,7 +64,7 @@ pub fn http(hyper_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>,
 	let engine = HttpWorker {
 		to_api,
 		from_api,
-		http_client: hyper_client,
+		http_client: shared_client.0,
 		requests: Vec::new(),
 	};
 
diff --git a/client/offchain/src/api/http_dummy.rs b/client/offchain/src/api/http_dummy.rs
index 5ff77a1068312..1c83325c93b20 100644
--- a/client/offchain/src/api/http_dummy.rs
+++ b/client/offchain/src/api/http_dummy.rs
@@ -19,8 +19,18 @@
 use sp_core::offchain::{HttpRequestId, Timestamp, HttpRequestStatus, HttpError};
 use std::{future::Future, pin::Pin, task::Context, task::Poll};
 
+/// Wrapper struct (wrapping nothing in case of http_dummy) used for keeping the hyper_rustls client running.
+#[derive(Clone)]
+pub struct SharedClient;
+
+impl SharedClient {
+	pub fn new() -> Self {
+		Self
+	}
+}
+
 /// Creates a pair of [`HttpApi`] and [`HttpWorker`].
-pub fn http() -> (HttpApi, HttpWorker) {
+pub fn http(_: SharedClient) -> (HttpApi, HttpWorker) {
 	(HttpApi, HttpWorker)
 }
 
diff --git a/client/offchain/src/lib.rs b/client/offchain/src/lib.rs
index 2562620fefa1f..7c90065746aa3 100644
--- a/client/offchain/src/lib.rs
+++ b/client/offchain/src/lib.rs
@@ -44,10 +44,9 @@ use sc_network::NetworkStateInfo;
 use sp_core::{offchain::{self, OffchainStorage}, ExecutionContext, traits::SpawnNamed};
 use sp_runtime::{generic::BlockId, traits::{self, Header}};
 use futures::{prelude::*, future::ready};
-use hyper_rustls::HttpsConnector;
-use hyper::{Client as HyperClient, Body, client};
 
 mod api;
+use api::SharedClient;
 
 pub use sp_offchain::{OffchainWorkerApi, STORAGE_PREFIX};
 
@@ -57,19 +56,19 @@ pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 	db: Storage,
 	_block: PhantomData<Block>,
 	thread_pool: Mutex<ThreadPool>,
-	hyper_client: Arc<HyperClient<HttpsConnector<client::HttpConnector>, Body>>,
+	shared_client: SharedClient,
 }
 
 impl<Client, Storage, Block: traits::Block> OffchainWorkers<Client, Storage, Block> {
 	/// Creates new `OffchainWorkers`.
 	pub fn new(client: Arc<Client>, db: Storage) -> Self {
-		let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
+		let shared_client = SharedClient::new();
 		Self {
 			client,
 			db,
 			_block: PhantomData,
 			thread_pool: Mutex::new(ThreadPool::new(num_cpus::get())),
-			hyper_client,
+			shared_client,
 		}
 	}
 }
@@ -125,7 +124,7 @@ impl<Client, Storage, Block> OffchainWorkers<
 				self.db.clone(),
 				network_state.clone(),
 				is_validator,
-				self.hyper_client.clone(),
+				self.shared_client.clone(),
 			);
 			debug!("Spawning offchain workers at {:?}", at);
 			let header = header.clone();

From 7af97498a2383b5d7405e27823db8fd97245da41 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Mon, 22 Jun 2020 16:45:48 +0200
Subject: [PATCH 6/8] Use lazy_static share SharedClient amongst
 OffchainWorkers. Remove the need to raise the fd limit

---
 Cargo.lock                      | 1 +
 client/offchain/Cargo.toml      | 1 +
 client/offchain/src/api/http.rs | 6 ------
 client/offchain/src/lib.rs      | 8 +++++++-
 4 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 75976823954a1..4b3c394329f26 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6570,6 +6570,7 @@ dependencies = [
  "futures-timer 3.0.2",
  "hyper 0.13.4",
  "hyper-rustls",
+ "lazy_static",
  "log",
  "num_cpus",
  "parity-scale-codec",
diff --git a/client/offchain/Cargo.toml b/client/offchain/Cargo.toml
index a9cd8c4deabbb..652c85dff2397 100644
--- a/client/offchain/Cargo.toml
+++ b/client/offchain/Cargo.toml
@@ -30,6 +30,7 @@ sp-runtime = { version = "2.0.0-rc3", path = "../../primitives/runtime" }
 sp-utils = { version = "2.0.0-rc3", path = "../../primitives/utils" }
 sc-network = { version = "0.8.0-rc3", path = "../network" }
 sc-keystore = { version = "2.0.0-rc3", path = "../keystore" }
+lazy_static = "1.4.0"
 
 [target.'cfg(not(target_os = "unknown"))'.dependencies]
 hyper = "0.13.2"
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index 7860a95c2142a..0d71542365d51 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -709,12 +709,6 @@ mod tests {
 	// server that runs in the background as well.
 	macro_rules! build_api_server {
 		() => {{
-			// We spawn quite a bit of HTTP servers here due to how async API
-			// works for offchain workers, so be sure to raise the FD limit
-			// (particularly useful for macOS where the default soft limit may
-			// not be enough).
-			fdlimit::raise_fd_limit();
-
 			let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
 			let (api, worker) = http(hyper_client.clone());
 
diff --git a/client/offchain/src/lib.rs b/client/offchain/src/lib.rs
index 7c90065746aa3..3ee29c88a5ac4 100644
--- a/client/offchain/src/lib.rs
+++ b/client/offchain/src/lib.rs
@@ -44,12 +44,18 @@ use sc_network::NetworkStateInfo;
 use sp_core::{offchain::{self, OffchainStorage}, ExecutionContext, traits::SpawnNamed};
 use sp_runtime::{generic::BlockId, traits::{self, Header}};
 use futures::{prelude::*, future::ready};
+use lazy_static::lazy_static;
 
 mod api;
 use api::SharedClient;
 
 pub use sp_offchain::{OffchainWorkerApi, STORAGE_PREFIX};
 
+lazy_static! {
+	// Using lazy_static to have the `SharedClient` shared amongst the different OffchainWorkers.
+	static ref SHARED_CLIENT: SharedClient = SharedClient::new();
+}
+
 /// An offchain workers manager.
 pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 	client: Arc<Client>,
@@ -62,7 +68,7 @@ pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 impl<Client, Storage, Block: traits::Block> OffchainWorkers<Client, Storage, Block> {
 	/// Creates new `OffchainWorkers`.
 	pub fn new(client: Arc<Client>, db: Storage) -> Self {
-		let shared_client = SharedClient::new();
+		let shared_client = SHARED_CLIENT.clone();
 		Self {
 			client,
 			db,

From fc822c4ae132e99b42314dd3ac1fcaebdea83e81 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Tue, 23 Jun 2020 10:34:42 +0200
Subject: [PATCH 7/8] Revert "Use lazy_static share SharedClient amongst
 OffchainWorkers. Remove the need to raise the fd limit"

This reverts commit 7af97498a2383b5d7405e27823db8fd97245da41.
---
 Cargo.lock                      | 1 -
 client/offchain/Cargo.toml      | 1 -
 client/offchain/src/api/http.rs | 6 ++++++
 client/offchain/src/lib.rs      | 8 +-------
 4 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 4b3c394329f26..75976823954a1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6570,7 +6570,6 @@ dependencies = [
  "futures-timer 3.0.2",
  "hyper 0.13.4",
  "hyper-rustls",
- "lazy_static",
  "log",
  "num_cpus",
  "parity-scale-codec",
diff --git a/client/offchain/Cargo.toml b/client/offchain/Cargo.toml
index 652c85dff2397..a9cd8c4deabbb 100644
--- a/client/offchain/Cargo.toml
+++ b/client/offchain/Cargo.toml
@@ -30,7 +30,6 @@ sp-runtime = { version = "2.0.0-rc3", path = "../../primitives/runtime" }
 sp-utils = { version = "2.0.0-rc3", path = "../../primitives/utils" }
 sc-network = { version = "0.8.0-rc3", path = "../network" }
 sc-keystore = { version = "2.0.0-rc3", path = "../keystore" }
-lazy_static = "1.4.0"
 
 [target.'cfg(not(target_os = "unknown"))'.dependencies]
 hyper = "0.13.2"
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index 0d71542365d51..7860a95c2142a 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -709,6 +709,12 @@ mod tests {
 	// server that runs in the background as well.
 	macro_rules! build_api_server {
 		() => {{
+			// We spawn quite a bit of HTTP servers here due to how async API
+			// works for offchain workers, so be sure to raise the FD limit
+			// (particularly useful for macOS where the default soft limit may
+			// not be enough).
+			fdlimit::raise_fd_limit();
+
 			let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
 			let (api, worker) = http(hyper_client.clone());
 
diff --git a/client/offchain/src/lib.rs b/client/offchain/src/lib.rs
index 3ee29c88a5ac4..7c90065746aa3 100644
--- a/client/offchain/src/lib.rs
+++ b/client/offchain/src/lib.rs
@@ -44,18 +44,12 @@ use sc_network::NetworkStateInfo;
 use sp_core::{offchain::{self, OffchainStorage}, ExecutionContext, traits::SpawnNamed};
 use sp_runtime::{generic::BlockId, traits::{self, Header}};
 use futures::{prelude::*, future::ready};
-use lazy_static::lazy_static;
 
 mod api;
 use api::SharedClient;
 
 pub use sp_offchain::{OffchainWorkerApi, STORAGE_PREFIX};
 
-lazy_static! {
-	// Using lazy_static to have the `SharedClient` shared amongst the different OffchainWorkers.
-	static ref SHARED_CLIENT: SharedClient = SharedClient::new();
-}
-
 /// An offchain workers manager.
 pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 	client: Arc<Client>,
@@ -68,7 +62,7 @@ pub struct OffchainWorkers<Client, Storage, Block: traits::Block> {
 impl<Client, Storage, Block: traits::Block> OffchainWorkers<Client, Storage, Block> {
 	/// Creates new `OffchainWorkers`.
 	pub fn new(client: Arc<Client>, db: Storage) -> Self {
-		let shared_client = SHARED_CLIENT.clone();
+		let shared_client = SharedClient::new();
 		Self {
 			client,
 			db,

From 531353412e581114405fdd9355d344ce930249c6 Mon Sep 17 00:00:00 2001
From: Scott Piriou <scott@parity.io>
Date: Tue, 23 Jun 2020 11:01:02 +0200
Subject: [PATCH 8/8] Add lazy_static for tests

---
 Cargo.lock                      |  2 +-
 client/offchain/Cargo.toml      |  2 +-
 client/offchain/src/api.rs      | 10 ++++------
 client/offchain/src/api/http.rs | 20 +++++++++-----------
 4 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 75976823954a1..2834c3ee4e6e0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6564,12 +6564,12 @@ version = "2.0.0-rc3"
 dependencies = [
  "bytes 0.5.4",
  "env_logger 0.7.1",
- "fdlimit",
  "fnv",
  "futures 0.3.4",
  "futures-timer 3.0.2",
  "hyper 0.13.4",
  "hyper-rustls",
+ "lazy_static",
  "log",
  "num_cpus",
  "parity-scale-codec",
diff --git a/client/offchain/Cargo.toml b/client/offchain/Cargo.toml
index a9cd8c4deabbb..819d6ac3a52c1 100644
--- a/client/offchain/Cargo.toml
+++ b/client/offchain/Cargo.toml
@@ -37,12 +37,12 @@ hyper-rustls = "0.20"
 
 [dev-dependencies]
 env_logger = "0.7.0"
-fdlimit = "0.1.4"
 sc-client-db = { version = "0.8.0-rc3", default-features = true, path = "../db/" }
 sc-transaction-pool = { version = "2.0.0-rc3", path = "../../client/transaction-pool" }
 sp-transaction-pool = { version = "2.0.0-rc3", path = "../../primitives/transaction-pool" }
 substrate-test-runtime-client = { version = "2.0.0-rc3", path = "../../test-utils/runtime/client" }
 tokio = "0.2"
+lazy_static = "1.4.0"
 
 [features]
 default = []
diff --git a/client/offchain/src/api.rs b/client/offchain/src/api.rs
index b4c414eb4748e..0aa5d4ad788ab 100644
--- a/client/offchain/src/api.rs
+++ b/client/offchain/src/api.rs
@@ -261,9 +261,9 @@ impl AsyncApi {
 		db: S,
 		network_state: Arc<dyn NetworkStateInfo + Send + Sync>,
 		is_validator: bool,
-		hyper_client: SharedClient,
+		shared_client: SharedClient,
 	) -> (Api<S>, Self) {
-		let (http_api, http_worker) = http::http(hyper_client);
+		let (http_api, http_worker) = http::http(shared_client);
 
 		let api = Api {
 			db,
@@ -293,8 +293,6 @@ mod tests {
 	use std::{convert::{TryFrom, TryInto}, time::SystemTime};
 	use sc_client_db::offchain::LocalStorage;
 	use sc_network::PeerId;
-	use hyper_rustls::HttpsConnector;
-	use hyper::{Client as HyperClient};
 
 	struct MockNetworkStateInfo();
 
@@ -312,14 +310,14 @@ mod tests {
 		let _ = env_logger::try_init();
 		let db = LocalStorage::new_test();
 		let mock = Arc::new(MockNetworkStateInfo());
-		let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
+		let shared_client = SharedClient::new();
 
 
 		AsyncApi::new(
 			db,
 			mock,
 			false,
-			hyper_client,
+			shared_client,
 		)
 	}
 
diff --git a/client/offchain/src/api/http.rs b/client/offchain/src/api/http.rs
index 7860a95c2142a..1f542b7c11e19 100644
--- a/client/offchain/src/api/http.rs
+++ b/client/offchain/src/api/http.rs
@@ -698,24 +698,22 @@ impl fmt::Debug for HttpWorkerRequest {
 mod tests {
 	use core::convert::Infallible;
 	use crate::api::timestamp;
-	use super::http;
+	use super::{http, SharedClient};
 	use sp_core::offchain::{HttpError, HttpRequestId, HttpRequestStatus, Duration};
 	use futures::future;
-	use std::sync::Arc;
-	use hyper::{Client as HyperClient};
-	use hyper_rustls::HttpsConnector;
+	use lazy_static::lazy_static;
+	
+	// Using lazy_static to avoid spawning lots of different SharedClients,
+	// as spawning a SharedClient is CPU-intensive and opens lots of fds.
+	lazy_static! {
+		static ref SHARED_CLIENT: SharedClient = SharedClient::new();
+	}
 
 	// Returns an `HttpApi` whose worker is ran in the background, and a `SocketAddr` to an HTTP
 	// server that runs in the background as well.
 	macro_rules! build_api_server {
 		() => {{
-			// We spawn quite a bit of HTTP servers here due to how async API
-			// works for offchain workers, so be sure to raise the FD limit
-			// (particularly useful for macOS where the default soft limit may
-			// not be enough).
-			fdlimit::raise_fd_limit();
-
-			let hyper_client = Arc::new(HyperClient::builder().build(HttpsConnector::new()));
+			let hyper_client = SHARED_CLIENT.clone();
 			let (api, worker) = http(hyper_client.clone());
 
 			let (addr_tx, addr_rx) = std::sync::mpsc::channel();