[pgpool-general: 7460] Re: Pgpool child process with pid: XXXXX was terminated by segmentation fault

[Madathala, Giridhar R]

BTW, I am  using Pgpool-II 4.2.2 with single instance of PostgreSQL as a backend node.  Also, after a series of segmentation fault errors pgpool going into a bad state with errors "ERROR:  Sorry, too many clients already".

Any pointers around the issue is really appreciated. Please let me know if need to raise a mantis ticket for tracking this issue.



2021-03-26 04:06:56: pid 17816: LOG:  fork a new child process with pid: 24196

2021-03-26 04:07:35: pid 17816: WARNING:  child process with pid: 23965 was terminated by segmentation fault

2021-03-26 04:07:35: pid 17816: LOG:  fork a new child process with pid: 24257

2021-03-26 04:08:20: pid 17816: WARNING:  child process with pid: 24189 was terminated by segmentation fault

2021-03-26 04:08:20: pid 17816: LOG:  fork a new child process with pid: 24314

2021-03-26 04:08:23: pid 17816: WARNING:  child process with pid: 24196 was terminated by segmentation fault

2021-03-26 04:08:23: pid 17816: LOG:  fork a new child process with pid: 24325

2021-03-26 04:08:43: pid 17816: WARNING:  child process with pid: 24181 was terminated by segmentation fault

2021-03-26 04:08:43: pid 17816: LOG:  fork a new child process with pid: 24348

2021-03-26 04:08:47: pid 24314: LOG:  failed to delete cache on memcached, error:"NOT FOUND"

2021-03-26 04:09:00: pid 24325: ERROR:  Sorry, too many clients already

2021-03-26 04:09:00: pid 24325: ERROR:  Sorry, too many clients already

2021-03-26 04:09:00: pid 24325: ERROR:  Sorry, too many clients already

2021-03-26 04:09:01: pid 20135: ERROR:  Sorry, too many clients already

2021-03-26 04:09:03: pid 17816: WARNING:  child process with pid: 24314 was terminated by segmentation fault

2021-03-26 04:09:03: pid 17816: LOG:  fork a new child process with pid: 24506

2021-03-26 04:09:04: pid 24506: ERROR:  Sorry, too many clients already

2021-03-26 04:09:07: pid 23723: ERROR:  Sorry, too many clients already


Thanks,
Giri
________________________________
From: Madathala, Giridhar R
Sent: Thursday, March 25, 2021 11:51 PM
To: pgpool-general at pgpool.net <pgpool-general at pgpool.net>
Subject: Pgpool child process with pid: XXXXX was terminated by segmentation fault

<mailto:pgpool-general at pgpool.net>Hi,

I have been running into segmentation fault errors with pgpool only when using in-memory caching (memory_cache_enabled = on).  When memory_cache_enabled is off, not really seeing any such issues. Any clue on what might be happening or if i missing something?


Pgpool errors:


2021-03-26 03:41:23: pid 17816: WARNING:  child process with pid: 18034 was terminated by segmentation fault

2021-03-26 03:41:23: pid 17816: LOG:  fork a new child process with pid: 19635

2021-03-26 03:43:19: pid 17816: WARNING:  child process with pid: 18720 was terminated by segmentation fault

2021-03-26 03:43:19: pid 17816: LOG:  fork a new child process with pid: 19683


Client App Errors (Java):


Caused by: org.postgresql.util.PSQLException: An I/O error occurred while sending to the backend.

at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:336) ~[postgresql-42.2.6.jar:42.2.6]

..
..

Caused by: java.io.EOFException

at org.postgresql.core.PGStream.receiveChar(PGStream.java:323) ~[postgresql-42.2.6.jar:42.2.6]





pgpool.conf configuration ( 1 backend node)


backend_clustering_mode = 'raw'
listen_addresses = '127.0.0.1'
port = 5432

backend_flag0 = 'ALWAYS_PRIMARY'

enable_pool_hba = on
pool_passwd = ''
authentication_timeout = 1min
allow_clear_text_frontend_auth = on
ssl = on

num_init_children = 48
max_pool = 6
listen_backlog_multiplier = 4
serialize_accept = on

memory_cache_enabled = on
memqcache_method = 'memcached'
memqcache_memcached_host = '127.0.0.1'
memqcache_memcached_port = 11211
memqcache_total_size = 128MB
memqcache_expire = 3600
memqcache_auto_cache_invalidation = on
memqcache_maxcache = 512kB
memqcache_cache_block_size = 1MB



Thanks,
Giri

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