Hi,
I have created my own dict server (proxy:[<dict path>]:<destination dict>) to access a proprietary database. The dict server basically creates a listing socket on a separate thread and then waits for incoming requests with accept(handle, NULL, 0). When a request comes in (i.e., when accept returns the accepted socket fd), the request is handed over to a handler thread (from a thread pool). The handler thread then read from the input.
The issue that I have is that if the read is done too fast after the accept, Dovecot reports a broken pipe:
dovecot: auth-worker(19904): Error: write(/usr/share/test-server/tmp/test-dict) failed: Broken pipe
This happens for almost all processes that try to access the dict server.
However If I add some sort of delay between the accept call and read (for example a sleep), everything works. No broken pipe even after testing with a large number of parallel requests for a long time. Somehow it looks like if the first read is done too fast, it takes a long time to read the data. During this time it looks like all other Dovecot processes are no longer able to connect and report the broken pipe. With the artificial delay, everything works ok and I can see that multiple incoming request are handled by multiple threads so it looks like Dovecot uses multiple auth worker processes. If however one connection hangs on the read it looks like no Dovecot proccess is able to connect
Any idea what might be causing the broken pipe in relation to timing of the read?
Kind regards,
Martijn