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Run calibre-2.60.0-2.fc24.x86_64 Minimize it, do not interact with it on network etc. strace -f it. Observe active polling loops with very short timeouts: [pid 26246] <... select resumed> ) = 0 (Timeout) [pid 26246] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 26242] <... select resumed> ) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 35727} <unfinished ...> [pid 26245] <... select resumed> ) = 0 (Timeout) [pid 26245] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 26247] <... select resumed> ) = 0 (Timeout) [pid 26247] select(0, NULL, NULL, NULL, {0, 100000} <unfinished ...> [pid 26242] <... select resumed> ) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 1000}) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 2000}) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 4000} <unfinished ...> [pid 26282] <... select resumed> ) = 0 (Timeout) [pid 26282] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 26242] <... select resumed> ) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 8000} <unfinished ...> [pid 26246] <... select resumed> ) = 0 (Timeout) [pid 26246] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 26242] <... select resumed> ) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 16000} <unfinished ...> [pid 26245] <... select resumed> ) = 0 (Timeout) [pid 26245] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 26242] <... select resumed> ) = 0 (Timeout) [pid 26242] select(0, NULL, NULL, NULL, {0, 32000} <unfinished ...> ... so the process sucks up processor time for no apparent reason.
Can you catch it eariler and see what exactly it's trying to poll here?
Did some random gdb backtraces, and it looks like it's all over the place; multiple threads doing multiple things. The calibre server functionality is part of it, but even with it turned off, we get other threads doing [pid 23766] <... select resumed> ) = 0 (Timeout) [pid 23766] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 23763] <... select resumed> ) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 1000}) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 2000}) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 4000}) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 8000}) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 16000}) = 0 (Timeout) [pid 23763] select(0, NULL, NULL, NULL, {0, 32000} <unfinished ...> [pid 23767] <... select resumed> ) = 0 (Timeout) [pid 23767] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 23766] <... select resumed> ) = 0 (Timeout) [pid 23766] select(0, NULL, NULL, NULL, {0, 50000} <unfinished ...> [pid 23763] <... select resumed> ) = 0 (Timeout) calibre uses several other downstream python libraries for communications & such, and a brief search didn't immediately identify a single calibre-side knob for general purpose polling intervals. For example, that 50000-us poll is done by : (gdb) py-bt Traceback (most recent call first): File "/usr/lib64/python2.7/threading.py", line 362, in wait _sleep(delay) File "/usr/lib64/python2.7/Queue.py", line 177, in get self.not_empty.wait(remaining) File "/usr/lib64/calibre/calibre/utils/ipc/server.py", line 246, in run job = self.add_jobs_queue.get(True, 0.2) File "/usr/lib64/python2.7/threading.py", line 804, in __bootstrap_inner self.run() File "/usr/lib64/python2.7/threading.py", line 777, in __bootstrap self.__bootstrap_inner() so that 0.2 could be way too small. Another thread: (gdb) thread 9 [Switching to thread 9 (Thread 0x2b240702f700 (LWP 23767))] #0 0x00002b23ca5d31c3 in select () at ../sysdeps/unix/syscall-template.S:84 84 T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS) (gdb) py-bt Traceback (most recent call first): File "/usr/lib64/python2.7/threading.py", line 362, in wait _sleep(delay) File "/usr/lib64/python2.7/threading.py", line 617, in wait self.__cond.wait(timeout, balancing) File "/usr/lib64/calibre/calibre/db/backup.py", line 44, in wait if self.stop_running.wait(interval): File "/usr/lib64/calibre/calibre/db/backup.py", line 50, in run self.wait(self.interval) File "/usr/lib64/python2.7/threading.py", line 804, in __bootstrap_inner self.run() File "/usr/lib64/python2.7/threading.py", line 777, in __bootstrap self.__bootstrap_inner() ... etc., so kind of all over. Just would be nice to whack one mole at a time until the strace quiets down.
It might be worth bringing this up upstream ( https://bugs.launchpad.net/calibre ) as he might know what areas might be causing this.
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