Leaking promise created at ConnectionPool.swift line 373

[fabianfett]

Hi,

I just checked out the current master commit 9cdd1dc and wanted to test it with my lambda-runtime.

When building for macOS in DEBUG, I ran immediately into a fatalError:

Fatal error: leaking promise created at (file: "/Users/xxx/Library/Developer/Xcode/DerivedData/xxx-brfbdomqotikxpeqafasrajmegus/SourcePackages/checkouts/async-http-client/Sources/AsyncHTTPClient/ConnectionPool.swift", line: 373): file /Users/xxx/Library/Developer/Xcode/DerivedData/xxx-brfbdomqotikxpeqafasrajmegus/SourcePackages/checkouts/async-http-client/Sources/AsyncHTTPClient/ConnectionPool.swift, line 373

This happens on the first invocation of execute.

I haven't found a similar issue here, so that's why I created one.

[Lukasa]

Hmm, this error could well be caused by a path where promises can be leaked if creating NIOSSLContext objects fail. Specifically:

async-http-client/Sources/AsyncHTTPClient/HTTPClient.swift

Lines 634 to 645 in 9cdd1dc

	do {
	let tlsConfiguration = tlsConfiguration ?? TLSConfiguration.forClient()
	let context = try NIOSSLContext(configuration: tlsConfiguration)
	let handlers: [ChannelHandler] = [
	try NIOSSLClientHandler(context: context, serverHostname: key.host.isIPAddress ? nil : key.host),
	TLSEventsHandler(completionPromise: handshakePromise),
	]
	return self.addHandlers(handlers)
	} catch {
	return self.eventLoop.makeFailedFuture(error)
	}

handshakePromise is passed to TLSEventsHandler here, but if the line above throws then it'll be leaked.

[Lukasa]

(The same logic applies to the return value of self.addHandlers which can also leak this promise if the returned future fails)

[fabianfett]

@Lukasa For reference I create a connection to http://localhost:7000.

[Lukasa]

Heh, yup, that promise can also be leaked if the connection attempt fails.

[Lukasa]

Lots of ways to leak that promise it seems.

[fabianfett]

Okay, besides the fact, that we shouldn't leak I found the issue, why it was happening to me. I tried to connect to http://http://127.0.0.1:7000. So I guess dns failed?

[Lukasa]

Yup, that sounds right.

[weissi]

CC @adtrevor

[PopFlamingo]

@fabianfett Thank you for reporting the issue, #180 should fix it 🙂
cc: @Lukasa @weissi