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Re: Session locks up and will not die - maybe a MySQL bug

Subject: Re: Session locks up and will not die - maybe a MySQL bug
From: Marek Wawrzyczny <email@hidden>
Date: Mon, 24 Nov 2003 09:53:31 +1100

The problem the email mentions does not appear to be purely MySQL. While yes, the MySQL settings for concurrent users and open files were low in his distribution, at the end of the article he says:

"It appeared that that the client process (which to this point had
been totally ignored) may be running out of file descriptors itself."

and

"This was fine for the MySQL server process, but for clients, it
was a disaster.  While the pid for the server process was discrete,
clients could be any process.  What we really needed to do was
alter the per process soft file descriptor limit."

Finally, the author of the email goes on to modify kernel source and recompiles the kernel to fix his problem where his client application is running out of file descriptors (not MySQL). The article suggests that:

a) If MySQL is the problem, you should see "Too many files open" messages in your MySQL logs. b) If you are NOT seeing these messages in your MySQL logs, then there is a problem purely with your WO application.

On Saturday, Nov 22, 2003, at 08:56 Australia/Sydney, Denis Stanton wrote:

Hi Denis
thank you for a superb piece of detective work in finding this report of a problem that may be the same as mine.

I have confirmed that I am using MySQL 4.0.14 on my server. What I can't find is any evidence that the problem report you referred name to has been recognized and fixed. The report you quoted was dated over a year ago. I've tried searching the MySQL bug list for "too many files" but I have not found anything that matches. I'm not very familiar with this sort of bug tracking so if anybody has experience of this I would appreciate the help.
The basic questions are:
1) Is it possible that MySQL 4.0.14 has a bug relating to file descriptor limits that can cause a "too many open files" messages in WebObjects 5.2.1? For example: [2003-11-21 12:00:37 NZDT] <WorkerThread138> <WOWorkerThread id=138 socket=null> IOException occurred while accepting server socket: java.net.SocketException: Too many open files

In my case this message was repeated over and over, with varying thread numbers, until WebObjects hung with a 635 MB log file full of these messages.

2) Is it possible that MySQL people have fixed this since 4.0.14? The latest build is 4.0.16. I could just install that, but I'd rather not disrupt my users unless I have reason to believe that the upgrade will actually help.
The report from Eric referred to maxusers being set too low at 32
In my standard MySQL set up I have:
	max_user_connections = 0
	open_files_limit = 0
Do you think I should change these? Zero is commonly used to mean "unlimited"

I would not know how to apply the fix Eric came up with, or really to determine whether it was required.
regards
Denis (Stanton)
On Saturday, November 22, 2003, at 07:21 AM, email@hidden wrote:
Hi
On Friday, November 21, 2003, at 12:30  am, Denis Stanton wrote:
[2003-11-21 12:00:37 NZDT] <WorkerThread195> <WOWorkerThread id=195 socket=null> IOException occurred while accepting server socket: java.net.SocketException: Too many open files
and so on for another 600+ MB.
Please can someone tell me what this means? Who has to many files? I just use EOM to communicate with a MySQL database. It looks like one file to me.

I'm using Mac OS X 10.2.8. WebObjects 5.2.1 and MySQL MySQL is either 4.0.14 or 4.0.16, I'm not sure if I updated the server/ My SQL connector is 3.0.1 or 3.0.9
You may need to upgrade MySQL. There was this problem:
http://mail-index.netbsd.org/netbsd-users/2002/09/02/0000.html
...Which is most likely fixed by now.
-- Denis.
Denis Stanton
email@hidden
Home:  (09) 533 0391
mobile: 021 1433622
Denis Stanton email@hidden Home: (09) 533 0391 mobile: 021 1433622 _______________________________________________ webobjects-dev mailing list | email@hidden Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev Do not post admin requests to the list. They will be ignored.


Marek Wawrzyczny

software engineer
-------------------------->
ish group pty ltd
7 Darghan St Glebe 2037 Australia
phone +61 2 9660 1400   fax +61 2 9660 7400
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Follow-Ups:
- Re: Session locks up and will not die - maybe a MySQL bug
  - From: Denis Stanton <email@hidden>

References:
	>Re: Session locks up and will not die - maybe a MySQL bug (From: Denis Stanton <email@hidden>)

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