[jira] [Commented] (THRIFT-4080) Unix sockets can get stuck forever

["James E. King III (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/THRIFT-4080?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16897657#comment-16897657 ] 

James E. King III commented on THRIFT-4080:
-------------------------------------------

The title is about unix sockets; how does this affect Unix sockets?

> Unix sockets can get stuck forever
> ----------------------------------
>
>                 Key: THRIFT-4080
>                 URL: https://issues.apache.org/jira/browse/THRIFT-4080
>             Project: Thrift
>          Issue Type: Bug
>          Components: Python - Library
>    Affects Versions: 0.10.0
>         Environment: Ubuntu 14.04
>            Reporter: David Fankhauser
>            Priority: Critical
>
> I had the problem that if the network connection is really bad the server sometimes does not accept more connections. "Really bad" means that a simple ping event sent via thrift could take 15 seconds.
> Having this issue for nearly 2 years now I could finally figure it out: 
> There is no timeout when the socket receives data. After a connection is established and the socket object is created, the connection can drop which yields to the socket blocking forever.
> I added a timeout in the TSocket accept function which makes the socket throw a resource not available error after 30 seconds:
> def accept(self):
>         client, addr = self.handle.accept()
>         -- added timeout of 30.0 seconds
>         client.setsockopt(socket.SOL_SOCKET, socket.SO_RCVTIMEO, struct.pack('LL', 30, 0))
>         result = TSocket()
>         result.setHandle(client)
>         return result
> Gives this error:
> buff = self.handle.recv(sz)
> error: [Errno 11] Resource temporarily unavailable
> I also tried using python socket's settimeout() function which does not work. Only setting the receive timeout times out dropped connections.
> This bug does not appear on stable connections. However, I have 4 devices that are connected via WiFi and my ThreadedServer gets stuck about 4-5 times a day.  The ThreadedServer has 5 threads, thus all 5 sockets get stuck all the time...
> FYI here is the strace of the stuck socket:
> [pid  2698] futex(0x7faf50000d80, FUTEX_WAIT_PRIVATE, 0, NULL <unfinished ...>
> [pid  2697] read(4,  <unfinished ...>
> [pid  2693] accept(7, {sa_family=AF_INET6, sin6_port=htons(39911), inet_pton(AF_INET6, "::ffff:46.125.249.41", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, [28]) = 6
> [pid  2693] recvfrom(6, 



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