Subject AW: [firebird-support] Memory usage excess / leak in FBServer 2.5.4
Author Jojakim Stahl

Hello Carlos,


Selecting mon$transactions multiple times shows every time different transactions. So no long running transaction active, but memory consumption is growing at a rate of ~30MB/hour.






Von: []
Gesendet: Freitag, 29. Mai 2015 13:35
An: 'Jojakim Stahl' joja.lists@... [firebird-support]
Betreff: Re: [firebird-support] Memory usage excess / leak in FBServer 2.5.4



Is there any chance that you are manipulating blobs variables inside procedures/triggers and the associated transaction is being left open?

Blob variable content (in memory) is static, meaning that each time you change the content of a blob variable, even a single byte change, Firebird will allocate new memory to store the whole blob content, so lots of memory can be consumed. The allocated memory is released only when the transaction commits.

Carlos H. Cantu -


I'm facing a problem where the firebird server v2.5.4 on win 2012 server in superserver mode is leaking memory. Currently I'm at ~5GB usage.

Don't have any idea how to track down the problem.
Thanks for any advice.


select * from mon$memory_usage where mon$stat_group=0;

MON$STAT_ID                     1
MON$STAT_GROUP                  0
MON$MEMORY_USED                 4570256632
MON$MEMORY_ALLOCATED            5314478080
MON$MAX_MEMORY_USED             4570448304
MON$MAX_MEMORY_ALLOCATED        5314678784

select * from mon$database;

MON$PAGE_SIZE                   8192
MON$ODS_MAJOR                   11
MON$ODS_MINOR                   2
MON$OLDEST_TRANSACTION          35186254
MON$OLDEST_ACTIVE               35186255
MON$OLDEST_SNAPSHOT             35186255
MON$NEXT_TRANSACTION            35187662
MON$PAGE_BUFFERS                16384
MON$SQL_DIALECT                 3
MON$SHUTDOWN_MODE               0
MON$SWEEP_INTERVAL              20000
MON$READ_ONLY                   0
MON$FORCED_WRITES               1
MON$RESERVE_SPACE               1
MON$CREATION_DATE               2015-04-15 08:58:37.1050
MON$PAGES                       250031
MON$STAT_ID                     1
MON$BACKUP_STATE                0

show version;
ISQL Version: WI-V2.5.4.26856 Firebird 2.5 Server version:
Firebird/x86-64/Windows NT (access method), version "WI-V2.5.4.26856 Firebird 2.5"
Firebird/x86-64/Windows NT (remote server), version "WI-V2.5.4.26856 Firebird 2.5/tcp (SV-W12-L900)/P12"
Firebird/x86-64/Windows NT (remote interface), version "WI-V2.5.4.26856 Firebird 2.5/tcp (SV-W12-L900)/P12"
on disk structure version 11.2