| From: | Li Japin <japinli(at)hotmail(dot)com> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
| Cc: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, "bharath(dot)rupireddyforpostgres(at)gmail(dot)com" <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, "pgsql-hackers(at)lists(dot)postgresql(dot)org" <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Terminate the idle sessions |
| Date: | 2020-08-31 02:40:37 |
| Message-ID: | 62AA3E9B-21B3-42E7-8118-7AEB964F7C36@hotmail.com |
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| Lists: | pgsql-hackers |
On Aug 31, 2020, at 8:51 AM, Thomas Munro <thomas(dot)munro(at)gmail(dot)com<mailto:thomas(dot)munro(at)gmail(dot)com>> wrote:
The main problem I have with it is the high frequency setitimer()
calls. If you enable both statement_timeout and idle_session_timeout,
then we get up to huge number of system calls, like the following
strace -c output for a few seconds of one backend under pgbench -S
workload shows:
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
39.45 0.118685 0 250523 setitimer
29.98 0.090200 0 125275 sendto
24.30 0.073107 0 126235 973 recvfrom
6.01 0.018068 0 20950 pread64
0.26 0.000779 0 973 epoll_wait
------ ----------- ----------- --------- --------- ----------------
100.00 0.300839 523956 973 total
Hi, Thomas,
Could you give the more details about the test instructions?
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