[GHC] #10629: threadWaitRead throws BlockedIndefinitelyOnMVar

[GHC]

#10629: threadWaitRead throws BlockedIndefinitelyOnMVar
-------------------------------------+-------------------------------------
        Reporter:                    |                   Owner:  simonmar
  facundo.dominguez                  |                  Status:  new
            Type:  bug               |               Milestone:
        Priority:  normal            |                 Version:  7.10.1
       Component:  Runtime System    |                Keywords:
      Resolution:                    |  concurrency sockets
Operating System:  Linux             |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------
Description changed by facundo.dominguez:

Old description:

> In a project using the network-transport-tcp package, I'm observing
> {{{threadWaitRead}}} throw the exception {{{BlockedIndefinitelyOnMVar}}}.
>
> The call stack is roughly:
>
> {{{
> ...
> n-t-tcp:Network.Transport.TCP.handleIncomingMessages
> n-t-tcp:Network.Transport.TCP.Internal.recvInt32
> n-t-tcp:Network.Transport.TCP.Internal.recvExact
> network:Network.Socket.ByteString:recv
> network:Network.Socket.ByteString:recvInner
> network:Network.Socket.Internal:throwSocketErrorWaitRead
> base:Control.Concurrent:threadWaitRead
> }}}
>
> IIUC this would be an RTS bug. The socket file descriptor is healthy and
> works fine if the exception is caught and {{{threadWaitRead}}} is
> retried.
>
> Unfortunately, I can only reproduce this in a particular machine and with
> a rather complex test case.
>
> I'd appreciate any advice on inspecting the RTS code to scan for the
> cause of {{{BlockedIndefinitelyOnMVar}}} being thrown.
>
> Of course, if someone can help explaining this behavior I'll be most
> thankful.

New description:

 In a project using the network-transport-tcp package, I'm observing
 {{{threadWaitRead}}} throw the exception {{{BlockedIndefinitelyOnMVar}}}.

 The call stack is roughly:

 {{{
 ...
 n-t-tcp:Network.Transport.TCP.handleIncomingMessages
 n-t-tcp:Network.Transport.TCP.Internal.recvInt32
 n-t-tcp:Network.Transport.TCP.Internal.recvExact
 network:Network.Socket.ByteString:recv
 network:Network.Socket.ByteString:recvInner
 network:Network.Socket.Internal:throwSocketErrorWaitRead
 base:Control.Concurrent:threadWaitRead
 }}}

 IIUC this would be an RTS bug. The socket file descriptor is healthy and
 works fine if the exception is caught and {{{threadWaitRead}}} is retried.

 Unfortunately, I can only reproduce this in a particular cluster and with
 a rather complex test case while using the threaded runtime.

 I'd appreciate any advice on inspecting the RTS code to scan for the cause
 of {{{BlockedIndefinitelyOnMVar}}} being thrown.

 Of course, if someone can help explaining this behavior I'll be most
 thankful.

--

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10629#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler