Description
Description
When debugging Hummingbird 2 in instruments, I've found that running a benchmark against a test app causes tasks to stay alive. This is paired with a slight bump in memory usage as well, which isn't being released. Upon inspection, the alive task tracker in the "Swift Tasks" instruments sees a continuous growth in both running and alive tasks.
In the attached graph, you'll see ~five tests in the time profiler. In reality, I ran nine of these tests total. Each test invoked wrk as such: wrk -c 128 -d 15s -t 8 http://localhost:8080. This is likely a glitch in the time profiler instrument, because WRK is in fact producing and receiving data. In addition, the alive and running tasks do continue to grow.
Initially, I thought that the tasks were kept alive by NIO or Hummingbird. In reality, the socket closes and I've added a marker at the start and end of each task to measure how many tasks were still running as far as Hummingbird is concerned. The counter went up to 128 and back to 0 as expected. This leads me to conclude that there's an edge case we're running into with DiscardingTaskGroup.
The line(s) in question are these: https://github.com/hummingbird-project/hummingbird/blob/2.x.x/Sources/HummingbirdCore/Server/Server.swift#L118-L120
This calls into HTTP1: https://github.com/hummingbird-project/hummingbird/blob/2.x.x/Sources/HummingbirdCore/Server/HTTP/HTTP1Channel.swift#L65
Finally calling into a generic HTTP handle function here: https://github.com/hummingbird-project/hummingbird/blob/2.x.x/Sources/HummingbirdCore/Server/HTTP/HTTPChannelHandler.swift#L43
Reproduction
Hummingbird 2 has a PerformanceTest application that reproduces this issue. Run that executable in Xcode Instruments with the concurrency tools. Then, after it's started, run wrk -c 128 -d 15s -t 8 http://localhost:8080 from your terminal.
Expected behavior
The amount of alive and running tasks decreases once TCP connections are closed.
Environment
Swift 5.9 as bundled with Xcode 15.2 (swiftc -version does not happen to be targeting the Xcode provided version)
Additional information
No response