2013-01-05 05:58 keltezéssel, Amit kapila írta:
On Friday, January 04, 2013 10:57 PM Boszormenyi Zoltan wrote:
Hi,
I am reviewing your patch.
Thank you very much.
Since you are using a constant string, it would be a little faster
to use "sizeof(string)-1" as it can be computed at compile-time
and not run the strlen() all the time this code is reached.
I have reffered the code just above for PG_TEMP_FILE_PREFIX in same function
sendDir().
I have that not only that place, but there other places where strlen is used
for PG_TEMP_FILE_PREFIX.
I think in this path, such optimization might not help much.
However if you think we should take care of this, then I can find other places
where similar change can be done
to make it consistent?
In create_conf_lock_file():
Can't we add a new LWLock and use it as a critical section instead
of waiting for 10 seconds? It would be quite surprising to wait
10 seconds when accidentally executing two SET PERSISTENT
statements in parallel.
Yes, you are right adding a new LWLock will avoid the use of sleep.
However I am just not sure if for only this purpose we should add a new LWLock?
Similar logic is used in CreateLockFile() for postmaster file but it doesn't
use sleep.
How about reducing the time of sleep or removing sleep, in that user might get
error and he need to retry to get his command successful?
I think removing the loop entirely is better.
However, the behaviour should be discussed by a wider audience:
- the backends should wait for each other just like other statements
that fight for the same object (in which case locking is needed), or
- throw an error immediately on conflicting parallel work
I also tried to trigger one of the errors by creating the lock file manually.
You need an extra space between the "... retry" and "or ...":
+ ereport(ERROR,
+ (errcode_for_file_access(),
+ errmsg("could not create lock file
\"%s\": %m ", LockFileName),
+ errhint("May be too many concurrent edit
into file happening, please wait!! and retry"
+ "or .lock is file
accidently left there please clean the file from config_dir")));
Best regards,
Zoltán Böszörményi
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Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de
http://www.postgresql.at/
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