.CORE files - HOw to STOP THEM!

[pooya]

Okay how do i make them stop .. its really annoying me now.

[青山 素子]

You can't. Only the host can either by disabling core dumps or fixing the issue.

How big are the files?

[pooya]

28 to 30mb each.. in a day it makes like 10 core files.

[青山 素子]

Can you send me one of the files via FTP? I probably won't be able to determine the cause, but I can at least figure out the program that created them.

[pooya]

Sure, moving it to a special folder and giving you the link.

[Joseph7]

I feel for ya. I am having the same problem on 2 different sites with SMF integrated. One site is a Subdreamer CMS with SMF integration. The other site is a Drupal CMS with SMF integration. I am assuming it is an SMF mod that is causing this problem. Until I can figure out which one I just delete the core dumps everyday.

[metallica48423]

i had core dumps occuring due to the AEVAC mod at one point... i think it was AEVAC 3

[pooya]

Crap i too have the addon .. uninstalling it to see :O

[青山 素子]

Okay, I analyzed the dump as best I could. Since I don't have the same binaries as the server, I can't get a reliable back trace.

Code Select Expand


Core was generated by `/usr/bin/php /xxxxxx/xxxxxxxxxx/public_html/index.php'.
Program terminated with signal 11, Segmentation fault.


So, the problem is in PHP or one of the libraries it uses.

[pooya]

oooooooo so it is one of the scripts which is casuing this ?

[aldo]

Possibly... I remember I was getting core dumps (like you) in my SMF directory, I uninstalled a modification and it stopped. I don't remember which one it was...

[pooya]

Well nope the avc didnt help much and yes motoko, when u open the page with firefox you can see the TONS of errors it shows and ie as well

[swtdivalove]

I just read something on this yesterday.  .CORE files are an HTTPD (Apache) Dump.  It means that there is an error in the Apache files and is causing Apache to crash.

Apache is a multi-thread, multi-server application.  It means that it can replicate itself if there is a high enough load on the the Apache daemon.

What the issue could be is that they do not have an allowance set high enough for reserve servers to run.  And, when Apache hits this limit, it crashes the HTTPD processes and you get a core dump.

I would find out which version of Apache is running on the server.

But, also... If there are any running processes that exceed the limit amount in Apache, this can also cause issues.

If it is a new version of Apache, it seems to be the cause.

I have Apache 2.2.10, the newest version and I'm seeing roughly similar things, but I am not getting any crashes on my web server.

But... .CORE files are directly related to Apache.

[青山 素子]

I just read something on this yesterday.  .CORE files are an HTTPD (Apache) Dump.  It means that there is an error in the Apache files and is causing Apache to crash.

Although Apache itself might be generating the dumps, it doesn't have to be the cause. Also, many hosts run things like PHP outside the Apache process and they could be responsible for the dump (as the original poster's dump showed).

Apache is a multi-thread, multi-server application.  It means that it can replicate itself if there is a high enough load on the the Apache daemon.

It depends on what MPM you are using. On Windows, it defaults to the WinNT MPM (a threaded model), but on Linux and UNIX systems, it uses the much more stable pre-fork MPM. Some hosts also run more experimental MPMs like worker (threaded) or perchild.

What the issue could be is that they do not have an allowance set high enough for reserve servers to run.  And, when Apache hits this limit, it crashes the HTTPD processes and you get a core dump.

I would find out which version of Apache is running on the server.

The core dump I examined showed the problem was with PHP itself, not Apache. Investigating the wrong thing won't help the poster.

But... .CORE files are directly related to Apache.

No, they can be generated by any process. The most common cause is when an application uses an invalid memory reference (SIGSEGV), although there are other causes.

You might want to get your knowledge straight before tossing out comments like this. I suggest reading the following manpages:

core(5)
signal(7)

[swtdivalove]

What I read was dealing strictly with Apache.  Don't remember the site otherwise I would point it out as I looked at a myriad of sites trying to deal with my own issue.  The only reason it caught my attention was that someone was asking about .CORE files.  The posters did not get into other areas.

But, since you want to jump on me for posting what someone else said, be my guest.  It seems to be the modus operandi.

[青山 素子]

I am sorry if you took offense to my post. The thing is that bad information (as in this case) is often worse than no information. Having bad information can cause you to waste time in the wrong area or even fiddle with something that isn't causing issues, breaking that too.

Once again, I am sorry if I was too harsh.

[swtdivalove]

I agree... But, one of the things you could do, as advice, is to show the person where they are wrong and give them a direction to go.

Consider it training someone.  You would not just tell them they are wrong, you would show them what they did is wrong.  Then point them in the right direction.  In this case, a link to a site that shows them information on the subject.  You don't necessarily need to give the answer, but let them discover on their own.

I apologize for coming off a tad rash.

But, I will point out that the information that I was looking at and reading in regards to this issue was the HTTPD daemon.  I now know that other processes and other applications can now cause this too.  Which will be furthering my training in web server admin'ing.

I do thank you for the information.

Also, I hope that this helps you as you are helping me.

Scratch your back and in turn mine gets scratched.

Have a good day Motoko-Chan.

[Nao 尚]

Just my 2 cents here. No solution offered -- just explaining how complicated it can be to get these fixed.

i had core dumps occuring due to the AEVAC mod at one point... i think it was AEVAC 3

Regarding this.
As Karl mentioned in another Core dump-related topic in the same board (thanks BTW), I managed to fix the issue in Aeva version 5.1.

I haven't been too vocal about the fix because (1) I never was able to get core dumps on either my server (even though it has PHP 5.2.6) or anyone else's, (2) it was too soon to be certain that it was fixed. But since I haven't got any complaint on that side since the release, I'll consider it as definitely fixed.

The bug was indeed due to the PHP stack getting filled too quick with a relatively lazy regular expression -- which was originally brought by the official PHP 5 documentation. I came up with two successives fixes which I applied to it (a ":" turned to ">" and an additional "?" to turn the regexp into a greedy one), and it fixed the bug. The crash would only happen when you had a long quote/code block inside a post. I don't remember the specifics. But on my server, it crashed with a 500 error code, which is possibly the vaguest error code you could find. So there is no "fixed" solution to the Core dumps -- if your server is simply not fit for your software, it might crash too soon. Regular expressions are a possible reason for the crashes, but not only these.

From what I could read in other core-related topics here, it can happen pretty much anywhere. The point is to be able to narrow down the piece of code that generates the crash, and then try to make it stricter (for instance in my case, making a regexp greedy instead of lazy). Even then, there are moments when Error 500 will happen outside the scope of a normal user visit. Not much can be done to debug these.

All I can say is, good luck, or if your errors aren't viewable by human beings, simply try to have Core dump automatic generation disabled.

[metallica48423]

Nao, FWIW,i have had absolutely zero coredumps since upgrading to 5.1, and i used to get them daily

[Nao 尚]

Good, good, thanks
I really spent two full days on this bug, it turned me crazy and everything... One of my most epic bug fights in the last few months