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Data Bases > Pgsql General > Re: Deadlock si...
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Re: Deadlock situation?

by daniel.armbrust.list@[EMAIL PROTECTED] ("Dan Armbrust") Apr 30, 2008 at 09:55 AM

>  Well, there went the evidence :-( ... but what exactly did you have
>  to do to shut it down?  I'm wondering whether the backends responded
>  to SIGINT or SIGTERM.

Sorry :(

First, I tried issuing a kill to the pid of the vacuum process.  It
didn't respond to kill.
Then, I tried a kill -9.  It responded to that :)

However, postgres got very unhappy at this point - I tried to log in
to issue another query against the pg_stat_activity table, but every
command I issued at this point simply hung.

In this case, Postgres had been started in the foreground on a
terminal, so I went to that terminal, and did a ctrl-c.  Eventually,
postgres stopped, but the terminal wouldn't respond either - and I had
to close it.

>
>  Next time, it'd be good to confirm (with top or vmstat or similar)
>  whether the backends are actually idle or are eating CPU or I/O.

I didn't notice any high load on the processor - the server seemed
idle.  But I didn't look real close a the individual postgres
processes.

>  Also try strace'ing a few of them; the pattern of kernel calls if
>  any would be revealing.
>
>  The lack of deadlock re****ts or 't' values in pg_stat_activity.waiting
>  says that you weren't blocking on heavyweight locks.  It's not
>  impossible that there was a deadlock at the LWLock level, though.
>
>  What sort of indexes are there on this table?

Here is the DDL for the table where vacuum was trying to run:

CREATE TABLE iphost
(
  ethernetmacaddr char(17) NOT NULL,
  cpemac char(11) NOT NULL,
  ipaddr varchar(15) NOT NULL,
  regtime timestamp NOT NULL,
  leasetime timestamp,
  last_updated timestamp NOT NULL DEFAULT now(),
  CONSTRAINT pk_iphost PRIMARY KEY (ethernetmacaddr, ipaddr),
  CONSTRAINT fk_iphost_cpe FOREIGN KEY (cpemac)
      REFERENCES cpe (cpemac) MATCH SIMPLE
      ON UPDATE CASCADE ON DELETE CASCADE
)
WITHOUT OIDS;
ALTER TABLE iphost OWNER TO pslogin;

CREATE INDEX ix_iphost_cpemac
  ON iphost
  USING btree
  (cpemac);

CREATE INDEX ix_iphost_ipaddr
  ON iphost
  USING btree
  (ipaddr);


> Teodor just fixed
>  an issue in GIN indexes that involved taking an unreasonable number of
>  LWLocks, and if that code wasn't exposing itself to deadlock risks
>  I'd be pretty surprised.
>
>                         regards, tom lane


Thanks.  If/when I can recreate this, I'll try to gather more info.

Dan

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 11 Posts in Topic:
Deadlock situation?
daniel.armbrust.list@[EMA  2008-04-29 16:54:48 
Re: Deadlock situation?
erik@[EMAIL PROTECTED] (  2008-04-29 17:10:31 
Re: Deadlock situation?
daniel.armbrust.list@[EMA  2008-04-29 17:30:55 
Re: Deadlock situation?
tgl@[EMAIL PROTECTED] (T  2008-04-29 22:20:06 
Re: Deadlock situation?
alvherre@[EMAIL PROTECTED  2008-04-29 18:33:59 
Re: Deadlock situation?
daniel.armbrust.list@[EMA  2008-04-30 09:55:25 
Re: Deadlock situation?
tgl@[EMAIL PROTECTED] (T  2008-04-30 11:33:35 
Re: Deadlock situation?
daniel.armbrust.list@[EMA  2008-04-30 11:17:23 
Re: Deadlock situation?
dan@[EMAIL PROTECTED]   2008-04-30 13:36:15 
Re: Deadlock situation?
daniel.armbrust.list@[EMA  2008-05-01 10:38:46 
Re: Deadlock situation?
scott.marlowe@[EMAIL PROT  2008-05-01 10:44:02 

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tan12V112 Mon Dec 1 19:13:41 CST 2008.