<div dir="ltr"><div class="gmail_default" style="font-family:arial,helvetica,sans-serif">jack clients and the server on linux communicate via reading and writing through a FIFO. there's nothing unusual about read(2) showing up here - the client has asked the server for a port disconnect and is waiting for a response.<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Nov 26, 2019 at 9:45 AM Ethan Funk <<a href="mailto:ethan@redmountainradio.com">ethan@redmountainradio.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="text-align:left;direction:ltr"><div>After days of testing, I got a crash (of sorts) out of my program. More of a hang than a crash. So I attached gdb to the process and looked around. My main thread appears to be hung deep inside a jack call, via jack_port_disconnect(). This is a point in my code where it cleans up after an jack-attached media player that is done playing. The player process terminates when it's jack connections are disconnected. I re-started the code execution and then stopped it again to find that the main thread was still waiting at the same libc_read() spot. After taking a look at the jack source code, I didn't find that jack_port_disconnect() would result in a read any place down the jack call chain. To be fair to jack, I am still mostly unfamiliar with the library structure, so I could be missing something. Any insight as to what I might be doing wrong? The port I am passing to jack_port_disconnect() appears to be valid, unless my code is overwriting memory. Backtrace of the main thread is below.</div><div><br></div><div>Thanks all.</div><div>Ethan...</div><div><br></div><div>(gdb) bt full</div><div>#0 __libc_read (nbytes=4, buf=0x7fffad4ed248, fd=5) at ../sysdeps/unix/sysv/linux/read.c:26</div><div> resultvar = 18446744073709551104</div><div> sc_cancel_oldtype = 0</div><div> __arg3 = <optimized out></div><div> _a2 = <optimized out></div><div> sc_ret = <optimized out></div><div> __value = <optimized out></div><div> __arg1 = <optimized out></div><div> _a3 = <optimized out></div><div> resultvar = <optimized out></div><div> resultvar = <optimized out></div><div> __arg2 = <optimized out></div><div> _a1 = <optimized out></div><div>#1 __libc_read (fd=5, buf=0x7fffad4ed248, nbytes=4) at ../sysdeps/unix/sysv/linux/read.c:24</div><div>No locals.</div><div>#2 0x00007fab6fe13ead in ?? () from /lib/x86_64-linux-gnu/libjack.so.0</div><div>No symbol table info available.</div><div>#3 0x00007fab6fe02e2a in ?? () from /lib/x86_64-linux-gnu/libjack.so.0</div><div>No symbol table info available.</div><div>#4 0x00007fab6fe03768 in ?? () from /lib/x86_64-linux-gnu/libjack.so.0</div><div>No symbol table info available.</div><div>#5 0x00007fab6fdf8598 in ?? () from /lib/x86_64-linux-gnu/libjack.so.0</div><div>No symbol table info available.</div><div>#6 0x0000564ac911610a in releaseQueueRecord (root=0x564ac9134260 <queueList>, rec=0x7fab3004c910, force=0 '\000') at data.c:473</div><div>[NOTE: this line is: jack_port_disconnect(mixEngine->client, *port); ]</div><div> c = 1</div><div> cmax = 2</div><div> port = 0x564acaf81278</div><div> prev = 0x564ac9134260 <queueList></div><div> current = 0x7fab3004c910</div><div> instance = 0x564acaf80be0</div><div> logID = 9126049</div><div> tmp = <optimized out></div><div>#7 0x0000564ac91057c5 in NextListItem (lastStat=2, curQueRec=0x564ac9134260 <queueList>, firstp=0x7fffad4ed418, sbtime=0x7fffad4ed41c, remtime=0, isPlaying=0x7fffad4ed416 "") at automate.c:811</div><div><br></div><div>.... Blah, blah, blah....</div></div>
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