Thread
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ERROR: out of shared memory
Sorin N. Ciolofan <ciolofan@ics.forth.gr> — 2007-03-26T12:32:08Z
Hello! I have to manage an application written in java which call another module written in java which uses Postgre DBMS in a Linux environment. I'm new to Postgres. The problem is that for large amounts of data the application throws an: org.postgresql.util.PSQLException: ERROR: out of shared memory Please, have you any idea why this error appears and what can I do in order to fix this? Are there some Postgre related parameters I should tune (if yes what parameters) or is something related to the Linux OS? Thank you very much With best regards, Sorin -
Re: [GENERAL] ERROR: out of shared memory
Tom Lane <tgl@sss.pgh.pa.us> — 2007-03-27T03:37:18Z
"Sorin N. Ciolofan" <ciolofan@ics.forth.gr> writes: > I have to manage an application written in java which call another module > written in java which uses Postgre DBMS in a Linux environment. I'm new to > Postgres. The problem is that for large amounts of data the application > throws an: > org.postgresql.util.PSQLException: ERROR: out of shared memory AFAIK the only very likely way to cause that is to touch enough different tables in one transaction that you run out of lock entries. While you could postpone the problem by increasing the max_locks_per_transaction setting, I suspect there may be some basic application misdesign involved here. How many tables have you got? regards, tom lane
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Re: [GENERAL] ERROR: out of shared memory
Merlin Moncure <mmoncure@gmail.com> — 2007-03-27T13:06:38Z
On 3/26/07, Tom Lane <tgl@sss.pgh.pa.us> wrote: > "Sorin N. Ciolofan" <ciolofan@ics.forth.gr> writes: > > I have to manage an application written in java which call another module > > written in java which uses Postgre DBMS in a Linux environment. I'm new to > > Postgres. The problem is that for large amounts of data the application > > throws an: > > org.postgresql.util.PSQLException: ERROR: out of shared memory > > AFAIK the only very likely way to cause that is to touch enough > different tables in one transaction that you run out of lock entries. > While you could postpone the problem by increasing the > max_locks_per_transaction setting, I suspect there may be some basic > application misdesign involved here. How many tables have you got? or advisory locks...these are easy to spot. query pg_locks and look for entries of locktype 'advisory'. I've already seen some apps in the wild that use them, openads is one. merlin
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Re: [GENERAL] ERROR: out of shared memory
Sorin N. Ciolofan <ciolofan@ics.forth.gr> — 2007-03-27T13:13:42Z
Dear Mr. Tom Lane, Thank you very much for your answer. It seems that the legacy application creates tables dynamically and the number of the created tables depends on the size of the input of the application. For the specific input which generated that error I've estimated a number of created tables of about 4000. Could be this the problem? With best regards, Sorin -----Original Message----- From: Tom Lane [mailto:tgl@sss.pgh.pa.us] Sent: Tuesday, March 27, 2007 6:37 AM To: Sorin N. Ciolofan Cc: pgsql-general@postgresql.org; pgsql-admin@postgresql.org; pgsql-performance@postgresql.org Subject: Re: [GENERAL] ERROR: out of shared memory "Sorin N. Ciolofan" <ciolofan@ics.forth.gr> writes: > I have to manage an application written in java which call another module > written in java which uses Postgre DBMS in a Linux environment. I'm new to > Postgres. The problem is that for large amounts of data the application > throws an: > org.postgresql.util.PSQLException: ERROR: out of shared memory AFAIK the only very likely way to cause that is to touch enough different tables in one transaction that you run out of lock entries. While you could postpone the problem by increasing the max_locks_per_transaction setting, I suspect there may be some basic application misdesign involved here. How many tables have you got? regards, tom lane
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Re: [GENERAL] ERROR: out of shared memory
Tom Lane <tgl@sss.pgh.pa.us> — 2007-03-27T13:59:15Z
"Sorin N. Ciolofan" <ciolofan@ics.forth.gr> writes: > It seems that the legacy application creates tables dynamically and the > number of the created tables depends on the size of the input of the > application. For the specific input which generated that error I've > estimated a number of created tables of about 4000. > Could be this the problem? If you have transactions that touch many of them within one transaction, then yup, you could be out of locktable space. Try increasing max_locks_per_transaction. regards, tom lane
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Re: ERROR: out of shared memory
Sorin N. Ciolofan <ciolofan@ics.forth.gr> — 2007-03-30T13:20:09Z
Dear Mr. Tom Lane, From what I've read from the postgresql.conf file I've understood that which each unit increasing of the "max_locks_per_transaction" parameter the shared memory used is also increased. But the shared memory looks to be already fully consumed according to the error message, or is the error message irrelevant and improper in this situation? With best regards, Sorin -----Original Message----- From: Tom Lane [mailto:tgl@sss.pgh.pa.us] Sent: Tuesday, March 27, 2007 4:59 PM To: Sorin N. Ciolofan Cc: pgsql-general@postgresql.org; pgsql-admin@postgresql.org; pgsql-performance@postgresql.org Subject: Re: [GENERAL] ERROR: out of shared memory "Sorin N. Ciolofan" <ciolofan@ics.forth.gr> writes: > It seems that the legacy application creates tables dynamically and the > number of the created tables depends on the size of the input of the > application. For the specific input which generated that error I've > estimated a number of created tables of about 4000. > Could be this the problem? If you have transactions that touch many of them within one transaction, then yup, you could be out of locktable space. Try increasing max_locks_per_transaction. regards, tom lane
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Re: ERROR: out of shared memory
Joseph Shraibman <jks@selectacast.net> — 2007-04-06T00:25:11Z
Try doing select * from pg_locks to see how many locks you have out.