Hi,
I've been trying to debug a weird situation on a Rails app (4.1) using
Unicorn (4.8.3).
Sometimes, some requests are hanging and I can't find why.
I've hooked "strace" to the workers and I have a lot of lines with
"Resource temporarily unavailable" and I wonder if it's normal.
Here is a snippet :
11587 write(7,
"\27\3\3\1\253\36\274d\263\340\375\250d\374~X\364\306^\227{F\357~\223\347\245M\351-\360\301"...,
432 <unfinished ...>
11581 read(3, <unfinished ...>
11587 <... write resumed> ) = 432 <0.000016>
11581 <... read resumed> 0x7f5b04878cc0, 1024) = -1 EAGAIN (Resource
temporarily unavailable) <0.000012>
11581 read(5, <unfinished ...>
11587 write(7,
"\27\3\3\t`+\22zIY\242\252L\346?n\245!\347c\251\341\fo\202Is\346\23\10\320\34"...,
2405 <unfinished ...>
11581 <... read resumed> "!", 1024) = 1 <0.000016>
11587 <... write resumed> ) = 2405 <0.000015>
11581 read(5, 0x7f5b04878cc0, 1024) = -1 EAGAIN (Resource
temporarily unavailable) <0.000014>
11587 read(7, <unfinished ...>
11581 poll([{fd=3, events=POLLIN}], 1, 100 <unfinished ...>
11587 <... read resumed> 0x7f5af47c0123, 5) = -1 EAGAIN (Resource
temporarily unavailable) <0.000009>
11587 futex(0x7f5b04885054, FUTEX_WAKE_OP_PRIVATE, 1, 1,
0x7f5b04885050, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1}) = 1 <0.000005>
1184 <... futex resumed> ) = 0 <0.000226>
11587 futex(0x7f5b0488508c, FUTEX_WAIT_PRIVATE, 231, NULL <unfinished ...>
1184 futex(0x7f5b0488508c, FUTEX_WAKE_OP_PRIVATE, 1, 1,
0x7f5b04885088, {FUTEX_OP_SET, 0, FUTEX_OP_CMP_GT, 1} <unfinished ...>
11587 <... futex resumed> ) = -1 EAGAIN (Resource
temporarily unavailable) <0.000015>
1184 <... futex resumed> ) = 0 <0.000009>
11587 futex(0x7f5b04885020, FUTEX_WAIT_PRIVATE, 2, NULL <unfinished ...>
1184 futex(0x7f5b04885020, FUTEX_WAKE_PRIVATE, 1 <unfinished ...>
11587 <... futex resumed> ) = -1 EAGAIN (Resource
temporarily unavailable) <0.000007>
1184 <... futex resumed> ) = 0 <0.000008>
Is there a better way to hook into a worker process when the request
is hanging, to see what it is doing ?
Also, I didn't find a way to instrument how a worker handles a request.
I was looking for a debug message when a new request is taken and when
it is returned.
Thanks for any help.
--
Jérémy Lecour :
http://jeremy.wordpress.com - http://twitter.com/jlecour
