Questions[hangs](server)

I'm experiencing a weird issue with nginx + PHP-FPM hosted web app build with Symfony2. Basically, from time to time, there's a request that is not handled, instead the browser shows that it's waiting to start receiving (the wheel in chrome is spinning counter-clockwise).

I have nothing in error logs there that would help me identify the issue, neither in app log itself (Symfony 2.8), nginx nor php-fpm logs.

What is weird is there's no timeout at all, which would suggest php-fpm didn't even receive that request (right?).

Perhaps there's anyone who did experience such issues before and may know the probable cause?

Should I provide anything that would seem relevant (config files?), please do not hesitate to ask in comments.

Can anyone advice what is going on with my setup. I have mysql server on ubuntu which periodically produce very high iowait. for long time up to 10-20 minutes. During this time system and database almost not available. Sit that using this database just hangs. I checked vmstat during this period and it shows numbers like below

 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
 1 22      0  34712   8260 583416    0    0   660   935   76   99  6  2 84  6
 0 25      0  34560   8280 582932    0    0 42360 27008 2304 1804  9  3  0 84
 0 29      0  34560   8320 583676    0    0 41160 21524 2360 1763  4  4  0 92
 3 20      0  35912   8328 581532    0    0 12940  6856  766  764  1  0  0 99
 1 30      0  34512   8348 581804    0    0  4532  3748  925 1373  4  4  0 92

so iowait is large. I am guessing MYSQL which has 4 gb configured for innodb pool and has database of size around 6-8 gb is swapping. During this time when I used df I saw that root drive almost full it was shown 95%. When I restarted mysql in couple minutes it restarted and all came back to norm. And space on root drive (10gb) came back to 25%. I am running mysql on ebs device on amazon ec2.

What are my options? Box is 8gb large instance of ubuntu 10.4.

I will appreciate any help as I was googling and trying to solve it for couple weeks already. Thanks

I have been running an ESXi 4.0 server for months with a couple of WinServer2003 and several Ubuntu Server 10.4 VMs. The performance has been impressive on 6GB i7 Asus P6T hardware.

Suddenly, a week ago, ssh logins to the Ubuntu VMs take 10 minutes when connecting over the LAN (over a WAN the connection (pipe) is broken long before that). When logging in to these VMs the password prompt arrives immediately, and failed passwords are responded to immediately.

But the moment I log in then the shell prompt appears and I hang for many minutes. Sometimes the connection hangs before the shell prompt appears and sometimes I can type in a command but the moment I hit return the machine hangs. 10 full minute later control returns and the VM is responsive.

NOTE: there are several Ubuntu VMs on the same host machine that are identical in all ways that I can tell. However, only one of the VMs displays this behavior. That is why I mention the ESXi host in passing - I don't think it has anything to do with the problem.

This behavior is never seen when I connect with the troubled-VM's console (through vSphere Client). From the console the Ubuntu VMs all respond beautifully.

I have seen: http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&externalId=1003496&sliceId=1&docTypeID=DT_KB_1_1&dialogID=229586372&stateId=1%200%20229588522 ...and since that relates to delays in seeing the password prompt that does not appear to be the solution here.

Any other suggestions very welcome - thank you.

I recently moved from a Dreamhost shared hosting account to a Linode 512mb VPS. The switch has been rather smooth for normal day to day operation of my site but some problems with MySQL have cropped up. A little background on my setup because I'm not sure if the problem is with MySQL or not:

• Ngnix 0.7.65
• Ubuntu 10.04 LTS
• MySQL 5.1.41

The problem I'm having is that whenever executing a query that is not part of the sites normal operation...(this could be anything from optimizing a table, to doing a SELECT COUNT, to running a delete query on a set of data)...prevents the entire web server from loading any pages. All pages on my site do have database calls, but pages that do not interact with the table I am working on still won't load. If you try and visit a page while one of these queries is executing the page will attempt to load for about a minute or so before Nginx throws the error "502 Bad Gateway." Obviously this isn't as much of a problem for a COUNT query that takes less than 5 seconds, but optimizing tables can bring the site from loading pages for 5+ minutes.

We have a script that runs nightly which pulls the top 100,000 records from our main table and stores it in a separate table for a rankings page. On Dreamhost when this script was executing the rankings pages of our site would be empty but the rest of the site would continue operating, however, on the VPS no page on the site will load until the ~6 minute query is done.

If anymore info would help please let me know and I would be happy to provide. I've searched this site and Google pretty relentlessly trying to find anybody else who had experienced a problem similar to this but can't find anything. Do you guys think this is simply a problem with MySQL, or could it be caused my Nginx? (on Dreamhost I had Apache).

Thanks.

We have moved one of our sites to a new server, which once in a while completely hangs. At first this happened very rarely, maybe once per month, but now it's starting to happen every day. By hangs, I mean that all the requests time out, and trying apache2ctl status, or apache2ctl graceful in a shell results in apache2ctl waiting indefinitely. Only issuing a apache2ctl restart brings it out of this state. I can't seem to find anything in the apache error logs, the access logs indicate that apache is indeed not serving requests.

Currently the server is mostly serving a single site, a rapidshare-like file sharing portal, serving around 1TB data. It is running ubuntu lucid, has 8GB of ram and a quad core intel xeon cpu, with apache-mpm-itk and PHP 5.2.11.

It has munin running on it, and at the times when apache is hanging, it is showing a very high number of threads (650+). The usual number of threads is around ~200, and it goes to 650 in about 1 hour of time. Running ps at this time reveals that it is indeed apache who has a lot of children running. CPU load/memory usage doesn't seem to be a problem, at the moment it's using only 1.1GB of RAM, and load is 0.05.

I have been told that Lighttpd, or nginx would have been a much better solution for this kind of site. I'm willing to switch, but I'd rather try and make it work with this setup. (the old server was running apache too)

Was mpm-itk a bad idea? I mostly chose it for the security of having each virtualhost run under a different user. It's running on the default configuration pulled from the package manager, which is bad I know, but I'm not sure which values I should tune.

I'm posting some values that might be relevant, please ask for anything else if needed:

Timeout 300
KeepAlive on
MaxKeepAliveRequests 100
KeepAliveTimeout 15

<IfModule mpm_prefork_module>
    StartServers          5   
    MinSpareServers       5   
    MaxSpareServers      10  
    MaxClients          150 
    MaxRequestsPerChild   0   
</IfModule>

So, what values should I be looking at? Is there anything particular that I should grep the logs for?