Hi all, I'm trying to further debug the problem I described in my earlier mail ( https://lists.zeromq.org/pipermail/zeromq-dev/2018-February/032303.html) so I decided to use Helgrind to find race conditions in my code.
My problem is that apparently Helgrind 3.12.0 is reporting race conditions against zmq::atomic_ptr_t<> implementation. Now I know that Helgrind has troubles with C++11 atomics but by looking at the code I see that ZMQ is not using them (note: I do have ZMQ_ATOMIC_PTR_CXX11 defined but I also have ZMQ_ATOMIC_PTR_INTRINSIC defined, so the latter wins!). In particular Helgrind 3.12.0 tells me that: ==00:00:00:11.885 29399== ==00:00:00:11.885 29399== *Possible data race during read of size 8 at 0xB373BF0 by thread #4* ==00:00:00:11.885 29399== Locks held: none ==00:00:00:11.885 29399== at 0x6BD79AB: *zmq::atomic_ptr_t<zmq::command_t>::cas*(zmq::command_t*, zmq::command_t*) (atomic_ptr.hpp:150) ==00:00:00:11.885 29399== by 0x6BD7874: zmq::ypipe_t<zmq::command_t, 16>::check_read() (ypipe.hpp:147) ==00:00:00:11.885 29399== by 0x6BD7288: zmq::ypipe_t<zmq::command_t, 16>::read(zmq::command_t*) (ypipe.hpp:165) ==00:00:00:11.885 29399== by 0x6BD6FE7: zmq::mailbox_t::recv(zmq::command_t*, int) (mailbox.cpp:98) ==00:00:00:11.885 29399== by 0x6BD29FC: zmq::io_thread_t::in_event() (io_thread.cpp:81) ==00:00:00:11.885 29399== by 0x6BD05C1: zmq::epoll_t::loop() (epoll.cpp:188) ==00:00:00:11.885 29399== by 0x6BD06C3: zmq::epoll_t::worker_routine(void*) (epoll.cpp:203) ==00:00:00:11.885 29399== by 0x6C18BA5: thread_routine (thread.cpp:109) ==00:00:00:11.885 29399== by 0x4C2F837: mythread_wrapper (hg_intercepts.c:389) ==00:00:00:11.885 29399== by 0x6E72463: start_thread (pthread_create.c:334) ==00:00:00:11.885 29399== by 0x92F901C: clone (clone.S:109) ==00:00:00:11.885 29399== ==00:00:00:11.885 29399== This conflicts with a previous write of size 8 by thread #2 ==00:00:00:11.885 29399== Locks held: 1, at address 0xB373C08 ==00:00:00:11.885 29399== at 0x6BD77F4: *zmq::atomic_ptr_t<zmq::command_t>::set*(zmq::command_t*) (atomic_ptr.hpp:90) ==00:00:00:11.885 29399== by 0x6BD7422: zmq::ypipe_t<zmq::command_t, 16>::flush() (ypipe.hpp:125) ==00:00:00:11.885 29399== by 0x6BD6DF5: zmq::mailbox_t::send(zmq::command_t const&) (mailbox.cpp:63) ==00:00:00:11.885 29399== by 0x6BB9128: zmq::ctx_t::send_command(unsigned int, zmq::command_t const&) (ctx.cpp:438) ==00:00:00:11.885 29399== by 0x6BE34CE: zmq::object_t::send_command(zmq::command_t&) (object.cpp:474) ==00:00:00:11.885 29399== by 0x6BE26F8: zmq::object_t::send_plug(zmq::own_t*, bool) (object.cpp:220) ==00:00:00:11.885 29399== by 0x6BE68E2: zmq::own_t::launch_child(zmq::own_t*) (own.cpp:87) ==00:00:00:11.885 29399== by 0x6C03D6C: zmq::socket_base_t::add_endpoint(char const*, zmq::own_t*, zmq::pipe_t*) (socket_base.cpp:1006) ==00:00:00:11.885 29399== Address 0xb373bf0 is 128 bytes inside a block of size 224 alloc'd ==00:00:00:11.885 29399== at 0x4C2A6FD: operator new(unsigned long, std::nothrow_t const&) (vg_replace_malloc.c:376) ==00:00:00:11.885 29399== by 0x6BB8B8D: zmq::ctx_t::create_socket(int) (ctx.cpp:351) ==00:00:00:11.885 29399== by 0x6C284D5: zmq_socket (zmq.cpp:267) ==00:00:00:11.885 29399== by 0x6143809: ZmqClientSocket::Config(PubSubSocketConfig const&) (ZmqRequestReply.cpp:303) ==00:00:00:11.885 29399== by 0x6144069: ZmqClientMultiSocket::Config(PubSubSocketConfig const&) (ZmqRequestReply.cpp:407) ==00:00:00:11.885 29399== by 0x61684EF: client_thread_main(void*) (ZmqRequestReplyUnitTests.cpp:132) ==00:00:00:11.886 29399== by 0x4C2F837: mythread_wrapper (hg_intercepts.c:389) ==00:00:00:11.886 29399== by 0x6E72463: start_thread (pthread_create.c:334) ==00:00:00:11.886 29399== by 0x92F901C: clone (clone.S:109) ==00:00:00:11.886 29399== Block was alloc'd by thread #2 Is this a known (and ignorable) issue with zmq::atomic_ptr_t<>? Thanks, Francesco
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