On Oct 26 14:36, Lavrentiev, Anton (NIH/NLM/NCBI) [C] wrote: > Hi, > > For now, I can only report the observed (mis) behavior of SYSV semop() call, > which (on the client side) gets manifested as the following: > > transport_layer_pipes::connect: lost connection to cygserver, error = 2 > > (this code then does a by-hand adjustment with semctl(SETVAL)). > > Note that there is a dedicated cygserver process running for my > single-threaded > application. > > Looking at the debugging output of cygserver, this is what I see in the log > (around the only time semctl() is logged there): > > cygserver: > /home/corinna/src/cygwin/cygwin-1.7.15/cygwin-1.7.15-1/src/cygwin-1.7.15/winsup/cygserver/transport_pipes.cc, > line 132: Try to create named pipe: \\.\pipe\cygwin-13a7ed34cc1953a9-lpc > cygserver: > /home/corinna/src/cygwin/cygwin-1.7.15/cygwin-1.7.15-1/src/cygwin-1.7.15/winsup/cygserver/transport_pipes.cc, > line 132: Try to create named pipe: \\.\pipe\cygwin-13a7ed34cc1953a9-lpc > > Note the double pipe creation call, and only a single "exit" log line such as: > cygserver: > /home/corinna/src/cygwin/cygwin-1.7.15/cygwin-1.7.15-1/src/cygwin-1.7.15/winsup/cygserver/sem.cc, > line 81: leaving (3416)
That's normal, AFAICS. Look into cygserver.cc, method server_submission_loop::request_loop(). It calls _transport->accept() in a loop. _transport->accept always prints the "Try to create" log message. Every time a client connects, it will return, the cleint request is put into the request queue, and then the loop returns to call _transport->accept(). So you see this log message one more time than clients have connected up to that point in time. > Cygserver does not stop (also, since SIGSYS is set to ignore in the program, > it also keeps running -- although, not always quite successfully once the > semop() > failure occurred.) > > The semaphore operations are very intensive; and involve arrays of 5 sems at > some times; also, there are quite large chunks of shmem updated every now > and then. > > I studied the source of cygserver, and noticed that pipe_instance > (transport_pipes.cc) > is not declared "volatile". This is strange because the compiler can > rearrange lines > of code that include this variable, otherwise. And that seems rather > critical. You could build cygserver with the variable set to volatile and see if it changes anything. But I doubt it. > Right now what I observe, is that SYSV IPC is unreliable, and I'm yet to > figure > out why; For testing it would be most helpful if you would create a STC. Ideally it would be the shortest possible code which allows to reproduce the issue. Other than that, is it possible that you just stumble over a restriction in the sizes of the IPC objects? Did you try to tweak /etc/cygserver.conf for a start? Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
