DNSClient possibly not thread safe

[adam-fowler]

It crashes in DNSClient.send. It looks like multiple threads can access dnsDecoder.messageCache at the same time. I got this crash with the following code

let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: 1)
let client = try await DNSClient.connectTCP(
                    on: eventLoopGroup.next(),
                    host: "1.1.1.1"
                ).get()
async let result = client.initiateAAAAQuery(host: hostname, port: 0).get()
async let result2 = client.initiateAAAAQuery(host: hostname, port: 0).get()
async let result3 = client.initiateAAAAQuery(host: hostname, port: 0).get()

[JaapWijnen]

Thanks for the code example! I'll take a look

[JaapWijnen]

@adam-fowler I made sure the message cache is only accessed from the event loop in #20 . Could you check if this works as expected for your dns setup?

[adam-fowler]

That seems to have fixed the crash

[JaapWijnen]

Awesome, I had some trouble testing myself because the requests after my first were timing out. What did you use to test?

[adam-fowler]

@JaapWijnen There might be a problem. It seems to stall sometimes now

[Joannis]

Closing this, as the issue was elsewhere for that project.