Strange situation on slave server - Mailing list pgsql-general

From Condor
Subject Strange situation on slave server
Date
Msg-id ec3ad009fe7f8d81fb2b4c14206d2c28@stz-bg.com
Whole thread Raw
Responses Re: Strange situation on slave server
List pgsql-general
Hello,

I have master - slave replication hot standby. Both server are linux
slackware64 current with postgresql 9.4.4.

Today when I logged to check some things on slave server I see on top
memory taken 26%. That was strange for me and I restart server.
Well, I checked after 40 minute and I see again replication process is
little growing. For 10 min about 1.0.


postgres 14162  0.0  0.7 6514656 190684 ?      S    11:50   0:00
/usr/bin/postgres -D /var/lib/postgres/database -F
postgres 14163  0.4  5.4 6517856 1341268 ?     Ss   11:50   0:26  \_
postgres: startup process   recovering 00000001000005E50000005E
postgres 14166  0.1  5.4 6517876 1335980 ?     Ss   11:50   0:09  \_
postgres: checkpointer process
postgres 14168  0.0  0.2 6517732 53276 ?       Ss   11:50   0:01  \_
postgres: writer process
postgres 14180  0.0  0.0  29888  2864 ?        Ss   11:50   0:01  \_
postgres: stats collector process
postgres 14183  0.2  0.0 6522488 5584 ?        Ss   11:50   0:15  \_
postgres: wal receiver process   streaming 5E5/5EE36000


Today our system is little bit average but slave server receive one wal
file every minute. As you can see checkpointer process and recovering is
5.4% and until I write the email,
I check them again and now is 6.0


postgres 14162  0.0  0.7 6514656 190684 ?      S    11:50   0:00
/usr/bin/postgres -D /var/lib/postgres/database -F
postgres 14163  0.4  6.0 6517856 1499868 ?     Ss   11:50   0:30  \_
postgres: startup process   recovering 00000001000005E500000072
postgres 14166  0.1  6.0 6517876 1497064 ?     Ss   11:50   0:10  \_
postgres: checkpointer process
postgres 14168  0.0  0.2 6517732 53276 ?       Ss   11:50   0:01  \_
postgres: writer process
postgres 14180  0.0  0.0  29888  2864 ?        Ss   11:50   0:01  \_
postgres: stats collector process
postgres 14183  0.2  0.0 6522488 5584 ?        Ss   11:50   0:18  \_
postgres: wal receiver process   streaming 5E5/72B49718


I have free memory:
Mem:  24634464k total, 14674532k used,  9959932k free,   324108k buffers
Swap:  6589196k total,     1872k used,  6587324k free, 11819140k cached


I try to use strace on process:

# strace -p 14163

lseek(9, 0, SEEK_END)                   = 381943808
lseek(23, 0, SEEK_END)                  = 376832
lseek(5, 3563520, SEEK_SET)             = 3563520
read(5,
"~\320\5\0\1\0\0\0\0`6C\345\5\0\0\344\7\0\0\0\0\0\0\0\0\0\0\333I\f\0"...,
8192) = 8192
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(9, 0, SEEK_END)                   = 381943808
lseek(5, 3571712, SEEK_SET)             = 3571712
read(5,
"~\320\5\0\1\0\0\0\0\2006C\345\5\0\0^\6\0\0\0\0\0\0Ja.\0\20\0\220h"...,
8192) = 8192
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(10, 0, SEEK_END)                  = 186392576
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(11, 0, SEEK_END)                  = 182566912
read(3, 0x7ffd2d7a60d0, 16)             = -1 EAGAIN (Resource
temporarily unavailable)
poll([{fd=3, events=POLLIN}], 1, 5000)  = ? ERESTART_RESTARTBLOCK
(Interrupted by signal)
--- SIGUSR1 {si_signo=SIGUSR1, si_code=SI_USER, si_pid=14183,
si_uid=1000} ---
write(4, "\0", 1)                       = 1
rt_sigreturn({mask=[]})                 = -1 EINTR (Interrupted system
call)
read(3, "\0", 16)                       = 1
read(6, 0x7ffd2d7a611f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(5, 3579904, SEEK_SET)             = 3579904
read(5,
"~\320\5\0\1\0\0\0\0\2406C\345\5\0\0\232\5\0\0\0\0\0\0\0\0\0\0*\231\1\0"...,
8192) = 8192
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(12, 0, SEEK_END)                  = 203612160
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(13, 0, SEEK_END)                  = 331071488
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(14, 0, SEEK_END)                  = 193331200
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(15, 0, SEEK_END)                  = 271171584
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(16, 0, SEEK_END)                  = 187580416
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(17, 0, SEEK_END)                  = 193257472
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(18, 0, SEEK_END)                  = 277381120
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(19, 0, SEEK_END)                  = 199884800
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(20, 0, SEEK_END)                  = 193396736
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(21, 0, SEEK_END)                  = 204808192
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(22, 0, SEEK_END)                  = 193355776
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(9, 0, SEEK_END)                   = 381943808
lseek(23, 0, SEEK_END)                  = 376832
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(9, 0, SEEK_END)                   = 381943808
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(24, 0, SEEK_END)                  = 374423552
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(25, 0, SEEK_END)                  = 1777664
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
lseek(24, 0, SEEK_END)                  = 374423552
read(6, 0x7ffd2d7a672f, 1)              = -1 EAGAIN (Resource
temporarily unavailable)
read(3, 0x7ffd2d7a60d0, 16)             = -1 EAGAIN (Resource
temporarily unavailable)
poll([{fd=3, events=POLLIN}], 1, 5000)  = ? ERESTART_RESTARTBLOCK
(Interrupted by signal)
--- SIGUSR1 {si_signo=SIGUSR1, si_code=SI_USER, si_pid=14183,
si_uid=1000} ---
write(4, "\0", 1)                       = 1
rt_sigreturn({mask=[]})                 = -1 EINTR (Interrupted system
call)


and continue...
That is the slave server only for mirroring database no any connections
and query ever run on him.

My question is this normal ?



Regards,
Hristo Simeonov



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