Occasional duplicate post attempts since 3.7.3 upgrade.

[IanB]

Since the upgrade to "vBulletin® Version 3.7.3" I have noticed I get occasional attempts at duplicate posting. Anybody else experiencing this?

The post does happen but it also triggers the forum duplicate protection.The following errors occurred with your submission:

1. This forum requires that you wait 30 seconds between posts. Please try again in 26 seconds.Sure I can ignore the repost offer and no harm done, but it is irritating.

[IanB]

Surely I am not the only one experiencing this.

[jeffy]

If I remember correctly, I posted one reply in the first browser window, then tried posting another reply immediately in a different thread in the second browser window and I had the same error. Maybe the mods can try?

[Guest]

It never happened to me.

[Guest]

I just tried to post the same message twice here as a joke and the system wouldn't let me do it.

[LoRd_MuldeR]

It happened to me a few times after about ~4000 posts. That is negligible.

Also I think when it happened, then it happened because the sever was too busy. It's some kind of sync problem, I guess...

[IanB]

Yes, now you mention it, it always seems to happen when the servers is sluggish, and the server seems sluggish more often these days. I will check the number of users next time it happens.

Problems like this can be diabolical, the last thing a busy server needs to do is start double processing things. :devil:

[Swede]

Beeing a bit picky about 'my' server I have to ask about some more details as to 'the server seems sluggish more often these days'.. I do honour myself beeing quite good at optimizing and staying on top of the 'load' and I don't see any signs of any 'sluggishness' at all.
There are times when this HP freezes, a problem that many others share with me, but then there's not 'sluggishness' it's just a complete freeze for a short while.
So, what's up with the 'more often these days'?

[Guest]

I saw only one instance in the last 6 months or so of "Server is too busy". It lasted for an hour.

Performance for me is stellar. Good job, Swede.

[IanB]

@Swede,

Yes you do an excellent job of making this site run very well, thank you.

I generally start using the site first thing in the morning, which will be about 20:00 GMT. The sluggishness is still only occasional and seems unrelated to large number of users. It manifest itself as no data coming down the wire for a short time between the header and the main post text of the thread display and now recently with the quick post update doing a similar pause and then sometimes claiming a duplicate post.

I have been watching for a new occurance to help clarify the parameters, but as Murphy would have it, the problem has gone away to sulk in the corner.

[IanB]

Bingo! This post just did it!

The pause in data flow was about 30 seconds.


Saturday November 1 22:54:16 GMT 2008


All times are GMT +11. The time now is 09:53.
Currently Active Users: 1372 (61 members and 1311 guests)

[Shinigami-Sama]

I get that duplicate post error every 6weeks or so, it does post it, but it tells me that I already posted it once
and only on short messages
I'd suspect a tcp retransmit made it send the request twice without saying that

[IanB]

@Shinigami-Sama,

Yes, those are the symptoms. I don't know about the TCP retry, it is more likely an application timeout/retry between the front end and the database.

[IanB]

@Swede,

I don't know if you have done any tuning but the sluggish/pausing problem seems to be occurring less.

I just got another occurrence of the false duplicate post a few minutes ago. There are only 585 users so it does not seem load related, unless there is some background DB cleanup skewing the performance.

[IanB]

@Swede,

Since the upgrade to 3.7.4 the Quick Reply attempts to double post practically every time, what was an occasional annoyance is now a continuous very irritating bug.

[Swede]

Well, I still can't reproduce it in any way (writing this in the Quick Reply) and since you're the only one reporting this it's more likely to be in your end (or at least somewhere close to you). Of course this wouldn't explain why it's becoming worse but I can assure you that there are no timeouts between apache and mySQL and that the server isn't slowing down. I will make some OS-upgrades this week so lets see if anything changes.

[littleD]

I duplicated post when i wanted immediately edit just written post. But didnt write anything and pushed back button (once or twice) in my browser.

[IanB]

@Swede,

Okay, I have started debugging this and the browser is actually doing the post twice. :(

I will have to install a javascript debugger to see what is really going on. Keep you posted.

[IanB]

Looks like vB_Default_Timeout=15000 is being exceeded in

http://forum.doom9.org/clientscript/vbulletin_quick_reply.js?v=374

function qr_ajax_post(B,A) {
if(YAHOO.util.Connect.isCallInProgress(qr_ajax)) {
YAHOO.util.Connect.abort(qr_ajax)
}
qr_repost=false;
qr_ajax=YAHOO.util.Connect.asyncRequest(
"POST",
B,
{
success:qr_do_ajax_post,
failure:qr_handle_error,
timeout:vB_Default_Timeout
},
SESSIONURL+"securitytoken="+SECURITYTOKEN+"&"+A)
}

[IanB]

Okay, I have the full scenario now. It is the 15 second timeout that is getting me.
The 15 seconds starts on entry to the YAHOO.util.Connect code.
The DNS servers for this site runs a 60 second TTL for forum.doom9.org.
The chain of DNS servers I get to use take a while (>15 seconds) to respond sometimes.
The JavaScript code has a race condition in it, it completes the form post BEFORE it honours the timeout.
On timeout the JavaScript code resubmits the post ... I get to see the annoying result.
The problem started with 3.7.3 because it grew the new fast "quick reply" javascript.
Swede, your server when finally connected to responds quite fast. ;)My workaround is to put an entry for forum.doom9.org in my hosts file.

This is going to bite me next time the forum server changes IP addresses. :devil:

I have posted before about problems the really short TTL for this site causes, any chance it can get fixed now.

I am surprised zoneedit.com allow you to configure such a short TTL it must really pound their servers. Most DNS admins crucify people who do this.

[Doom9]

I never configured any TTL except in my multicast audio streaming app I developed for work.. Once I can get into my account again I'll see if there's an option to configure that.

[Doom9]

Finally they restored my access.. I changed the ttl under the soa settings from 60 to 3600 seconds. Let me know if that's better.

[IanB]

Thanks! :D I have removed my local host file entry, initially it still looks fine, I will keep you posted. ;)

[Doom9]

It's been a while.. any updates? Is it all OK now?

[IanB]

Yes, thank you, it has been working faultlessly. :D

The timeout methodology in the javascript, which allowed the issue to come to light, probably should be reported to JelSoft, so other internet performance problems do not weird out the forum. ;)

[Shinigami-Sama]

just happened in the coreavc thread to me