Kbase 20548: SonicMQ: Why Did My Broker Take Longer To Start This Time?
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
10/16/2008 |
|
Status: Unverified
GOAL:
How recovery can affect startup time.
GOAL:
How recovery upon startup of the broker.
FACT(s) (Environment):
SonicMQ 2000.x
SonicMQ 3.x.
FIX:
The two recovery log files, recoverylog1.bin and recoverylog2.bin, help ensure that when a SonicMQ broker is restarted, it is restored to exactly the same state as it was when it was shut down. These files reside in the directory indicated by the broker.ini parameter LOG_PATH.
As the broker processes persistent messages, opens or commits transactions, etc., it records this information in a recovery log file. At regular intervals, it writes out a summary of its current state. This is known as a syncpoint.
Upon startup, the broker sequentially processes the information that is recorded in the log file, beginning with the last syncpoint. This process is known as recovery.
When shutdown from an administrative client (such as Explorer or the Adminshell), part of the broker's shutdown process is to perform a syncpoint. This means that the next time it is started, the recovery process is very quick and all the information to be recovered is recorded in the syncpoint.
If the broker terminates unexpectedly, as when it is killed with CTRL-C, or if the machine on which it is running goes down, it cannot perform a syncpoint. Now, when it is subsequently restarted, recovery begins with the last syncpoint, then continues through all information that was written to the recovery log after that syncpoint. This is why startup after an unexpected shutdown takes longer than it does after the broker has been shut down in an orderly fashion from an
administrative client.
In SonicMQ 3.5, progress messages were added to the broker's startup process, so that the broker's output on startup indicates when the recovery process is taking place. In earlier versions of SonicMQ, startup may appear to pause after the message indicating whether security is enabled or disabled; this is when the recovery process takes place.