[Koha] Slow Koha OPAC login process
Michael Kuhn
mik at adminkuhn.ch
Wed Apr 19 02:31:21 NZST 2017
Hi Jonathan
I made a new attempt to use strace which has a different and much
shorter output:
1. I made a login attempt.
2. As soon as I saw the query was taking 99% of the CPU I picked the PID
(here: 63895) from the output of "top" and executed the following command:
# strace -c -p 63895
When the login finally succeeded I ended strace with CTRL+C. The output
then looked like the following (output can also be seen via
http://adminkuhn.ch/download/strace.txt):
Process 63895 attached
^CProcess 63895 detached
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
0.00 0.000000 0 146 read
0.00 0.000000 0 137 write
0.00 0.000000 0 8 open
0.00 0.000000 0 13 close
0.00 0.000000 0 54 22 stat
0.00 0.000000 0 19 fstat
0.00 0.000000 0 5 lstat
0.00 0.000000 0 123 poll
0.00 0.000000 0 16 2 lseek
0.00 0.000000 0 404 brk
0.00 0.000000 0 202 6 rt_sigaction
0.00 0.000000 0 416 rt_sigprocmask
0.00 0.000000 0 12 12 ioctl
0.00 0.000000 0 2 select
0.00 0.000000 0 4 alarm
0.00 0.000000 0 1 accept
0.00 0.000000 0 2 getpeername
0.00 0.000000 0 2 getsockopt
0.00 0.000000 0 2 kill
0.00 0.000000 0 11 fcntl
0.00 0.000000 0 4 getdents
0.00 0.000000 0 1 getcwd
0.00 0.000000 0 3 chdir
0.00 0.000000 0 1 unlink
0.00 0.000000 0 2 geteuid
0.00 0.000000 0 1 getegid
0.00 0.000000 0 2 getgroups
0.00 0.000000 0 4 prctl
0.00 0.000000 0 2 openat
------ ----------- ----------- --------- --------- ----------------
100.00 0.000000 1599 42 total
I wonder if this output is helpful?
Best wishes: Michael
Am 18.04.2017 um 16:02 schrieb Jonathan Druart:
> Use `strace -c -p PID` and paste the whole output please (hastebin or
> similar)
>
>
> On Tue, 18 Apr 2017 at 10:23 Michael Kuhn <mik at adminkuhn.ch> wrote:
>
>> Hi Marc and Jonatahn
>>
>> Marc wrote:
>>
>>> What version of Koha is it?
>>
>> We're running a new host with Debian GNU/Linux 8 and Koha 16.11.04.
>>
>>> Do you have errors or messages in the log files?
>>> You can monitor them using tail. At first place I would have a look at
>>> opac-error.log and plack-error.log,
>>> something like: tail -f opac-error.log
>>
>> No, they are no errors or messages. As soon as the login attempt in the
>> Koha OPAC is made the, the following process taking 99% of the CPU can
>> be seen with "top" or "ps -ef":
>>
>> phsh-ko+ 62293 26131 30 14:39 ? 00:00:22
>> /usr/share/koha/opac/cgi-bin/opac/opac-user.pl
>>
>> When the login finally succeeds (after maybe 30 seconds) the following
>> is written in the file "plack.log":
>>
>> 178.238.175.156 - - [18/Apr/2017:14:40:28 +0200] "POST
>> /opac/opac-user.pl HTTP/1.1" 200 26320
>> "http://bibliothek.phsh.ch/cgi-bin/koha/opac-main.pl?logout.x=1"
>> "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:52.0) Gecko/20100101
>> Firefox/52.0"
>>
>> But nothing is written to the file "opac-error.log".
>>
>> Jonathan wrote:
>>
>> > In production I am not aware of something you could do (well there is
>> > strace if you are patient and quick :D)
>> > In test you could use a code profiler or tell mysql to log slow
>> > queries.
>> > But the code profiler will be hazardous if it does not happens 100%
>> > of the time and htop would have told you if mysql was the culprit.
>>
>> I activated the Mysql slow query log during runtime, using the following
>> commands:
>>
>> mysql> set global log_slow_queries = 1;
>> mysql> set global slow_query_log_file = '/tmp/slow.txt';
>>
>> Then I made another login attempt in the Koha OPAC. The file
>> "/tmp/slow.txt" is created but it doesn't list any slow query, so I
>> think the problem is not in the query itself:
>>
>> # more /tmp/slow.txt
>> /usr/sbin/mysqld, Version: 5.5.54-0+deb8u1 ((Debian)). started with:
>> Tcp port: 3306 Unix socket: /var/run/mysqld/mysqld.sock
>> Time Id Command Argument
>>
>> Then I made some attempt to use strace, but I'm not sure how to really
>> use it and especially how to interpret the output... So what i've tried is:
>>
>> 1. I made a login attempt
>>
>> 2. As soon as I saw the query was taking 99% of the CPU i picked the PID
>> (here: 62503) from the output of "top" and executed the following command:
>>
>> # strace -p 62503
>>
>> The output then looked like the folloing (full output at the end of this
>> email):
>>
>> Process 62503 attached
>>
>> followed by many many lines like the following:
>>
>> brk(0xb63b000) = 0xb63b000
>> brk(0xb65c000) = 0xb65c000
>> brk(0xb67d000) = 0xb67d000
>>
>> Then after about 30 seconds it says:
>> [SKIP]
>>
>> At this point the login attempt finally succeeds. Actually I have no
>> idea what this means - can you please help?
>>
>> Best wishes: Michael
>> --
>> Geschäftsführer · Diplombibliothekar BBS, Informatiker eidg. Fachausweis
>> Admin Kuhn GmbH · Pappelstrasse 20 · 4123 Allschwil · Schweiz
>> T 0041 (0)61 261 55 61 <+41%2061%20261%2055%2061> · E mik at adminkuhn.ch ·
>> W www.adminkuhn.ch
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--
Geschäftsführer · Diplombibliothekar BBS, Informatiker eidg. Fachausweis
Admin Kuhn GmbH · Pappelstrasse 20 · 4123 Allschwil · Schweiz
T 0041 (0)61 261 55 61 · E mik at adminkuhn.ch · W www.adminkuhn.ch
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