I have a C++ client, that connects to a C# server. The connection is being
made by a RPC function (called
*InitializeStream()*), that sends a single request and receives a stream of
responses from the server. This RPC function is executed with 'max' timeout
(if the server is unavailable, later call to stream->Read() will return an
error. This is good enough for me).
I encountered a weird bug, which happened on a VM. (I couldn't reproduce it
on any other machine, but it reproduces easily on that VM). On that single
VM, the
*InitializeStream()* RPC function never returns.
Further debugging of this issue reveled the following:
1. The main thread (thread #1) is blocked inside InitializeStream(), in
* grpc_iocp_work()*. The exact line is
* iocp_windows.c@83* - in Windows's
* GetQueuedCompletionStatus()* function.
As far as I understand, here we wait for a task completion, for
unlimited timeout (I used the 'max' timeout).
[External Code]
> Test.exe!grpc_iocp_work(grpc_exec_ctx * exec_ctx, gpr_timespec deadline
) Line 83 C
Test.exe!grpc_pollset_work(grpc_exec_ctx * exec_ctx, grpc_pollset *
pollset, grpc_pollset_worker * * worker_hdl, gpr_timespec now,
gpr_timespec deadline) Line 140 C
Test.exe!grpc_completion_queue_pluck(grpc_completion_queue * cc, void *
tag, gpr_timespec deadline, void * reserved) Line 614 C
Test.exe!grpc::CoreCodegen::grpc_completion_queue_pluck(grpc_completion_queue
* cq, void * tag, gpr_timespec deadline, void * reserved) Line 70 C++
Test.exe!grpc::CompletionQueue::Pluck(grpc::CompletionQueueTag * tag)
Line 230 C++
Test.exe!grpc::ClientReader<test::TestRequest>::ClientReader<test::
TestRequest><test::InitMessage>(grpc::ChannelInterface * channel, const
grpc::RpcMethod & method, grpc::ClientContext * context, const test::
InitMessage & request) Line 151 C++
Test.exe!test::testInterface::Stub::InitializeStreamRaw(grpc::
ClientContext * context, const test::InitMessage & request) Line 46 C++
Test.exe!test::testInterface::Stub::InitializeStream(grpc::
ClientContext * context, const test::InitMessage & request) Line 86 C++
Test.exe!WinMain(HINSTANCE__ * __formal, HINSTANCE__ * __formal, char *
__formal, int __formal) Line 17 C++
[External Code]
2. One of gRPC's threads [from the thread pool] (thread #2), called the
function
* do_request_thread()* in
* resolve_address_windows.c@153*, which called
* grpc_blocking_resolve_address()* (blocking function, by its name) that
called
* getaddrinfo()* that never returns!
My guess is that thread #1 waits (*GetQueuedCompletionStatus*) for thread
#2's task completion.
*getaddrinfo()* never returns, so
*GetQueuedCompletionStatus()* is blocking, and the main thread is stuck.
Have you encountered this error before? Do you have any idea what can I do
(beside adding a timeout to the function, which I consider as a bypass and
not a solution).
I use gRPC v1.2.0 for both C++ and C#.
Thanks
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