enforce to close accepted connection after processing #2883
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lib/go/thrift/simple_server.go
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| @@ -211,6 +211,10 @@ func (p *TSimpleServer) innerAccept() (int32, error) { | |||
| select { | |||
| case <-ctx.Done(): | |||
| // client exited, do nothing | |||
| if client != nil { | |||
| client.Close() | |||
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can you explain more why do we need to close the client here? is there any connection leak otherwise?
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Yes, if the call to Close is not called, then any dynamically allocated data in client object is lost forever and hence the caller's golang runtime keeps eating memory.
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How would that affect overall performance, e.g. when doing multiple calls?
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Could you help clarify what is your overall performance concern?
Below is my understanding of how the simpleServer works with its serverTransport regarding accept an incoming request. Please correct me if I miss anything.
A client object is created by calling the underlying serverTransport.Accept(). I think client.Close() is to signal serverTransport that thrift server has finished using this client. So serverTransport could do whatever is required on its part, either to cleanup or recycle the object for reuse.
Without the signal from thrift server, what is expected from serverTransport to manage client object created by itself? The reference to client is lost after processing the request.
I guess thrift simple server has some assumption on how serverTransport to manage client created by serverTransport itself. Could you help advise where I could find the assumption? Or help explain the choice why not to enforce close client after processing.
Thanks for helping to review.
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I simply asked a question. If your answer is a validated "No it will not affect perf because ..." that's fine with me.
lib/go/thrift/simple_server.go
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| @@ -270,6 +274,7 @@ func (p *TSimpleServer) Stop() error { | |||
| } | |||
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| <-ctx.Done() | |||
| p.stopChan = nil | |||
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this does nothing, it's immediately overwritten by the next line
lib/go/thrift/simple_server.go
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| @@ -356,6 +361,7 @@ func (p *TSimpleServer) processRequests(client TTransport) (err error) { | |||
| ok, err := processor.Process(ctx, inputProtocol, outputProtocol) | |||
| if errors.Is(err, ErrAbandonRequest) { | |||
| err := client.Close() | |||
| client = nil | |||
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this does not work as you expected.
here client is the local arg of processRequests function, setting it to nil only affects that copy of client. it does not affect the client you are checking on line 214, which is at the caller of processRequests.
the whole nil checking regarding client is also unnecessary, if client is already closed, closing it again will only give you an already closed error, which you ignored anyways (on line 215).
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Makes sense. Then is it good to have defer client.Close in processRequests()?
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I would prefer to defer it in innerAccept instead.
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please fix the failed unit test. |
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@fishy I updated to fix golang unit test. Now I see there is build error due to python test. I dont understand how that is related to my changes. Could you help me understand what I need to fix? |
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@jshen14 sorry I missed your comment last year 😓 please rebase your change on top of latest master branch and the python tests should be fixed now. |
Enforce close of accepted connection in golang simple server to avoid memory leak
[skip ci]anywhere in the commit message to free up build resources.