We're currently running a multisite wordpress environment on a VPS at VPS.net. One of our websites, a blog that posts tests on a daily basis, seems to be the cause of our servers memory filling up. It has an average of 500 unique visitors a day and 1000 pageviews.
After the daily post our server crashed. First the memory fills and then the swap space. After approx 2 minutes the server becomes unresponsive.
The blog in question currently has the following URL structure: /%postname%/
After checking plugins the only reason why the server crashes that I can think of is the URL structure.
The server has 4 cores:
- 2.5 GHz of dedicated CPU
- 1.5 GB of RAM
This should be sufficient to run a decent multisite environment to my knowledge.
We've installed the following major plugins:
- W3 Total Cache (caching with APC, minify for CSS disabled, MaxCDN for our content delivery network).
- WordPress SEO by Yoast
- Gravity Forms Pro
- Analytics 360
- Codestyling Localization
- Clean Options
- Events Manager
- Lightbox 2
- Pretty Link Pro
- Quotes Collection
- Search and Replace
- Sexy Bookmarks
- MU Domain Mapping
- WP Smushit
- WP Audio
When the server crashes I get the following messages (as you can see swap space is full):
May 25 03:07:48 vps1 kernel: DMA: 76*4kB 2*8kB 1*16kB 0*32kB 1*64kB 0*128kB 0*256kB 0*512kB 1*1024kB 1*2048kB 4*4096kB = 19856kB May 25 03:07:48 vps1 kernel: DMA32: empty May 25 03:07:48 vps1 kernel: Normal: empty May 25 03:07:48 vps1 kernel: HighMem: empty May 25 03:07:48 vps1 kernel: 60612 pagecache pages May 25 03:07:48 vps1 kernel: Swap cache: add 455831, delete 456009, find 31353/52926, race 1+13 May 25 03:07:48 vps1 kernel: Free swap = 0kB May 25 03:07:48 vps1 kernel: Total swap = 1048568kB May 25 03:07:48 vps1 kernel: Free swap: 0kB May 25 03:07:48 vps1 kernel: 6162432 pages of RAM May 25 03:07:48 vps1 kernel: 123639 reserved pages May 25 03:07:48 vps1 kernel: 17405 pages shared May 25 03:07:48 vps1 kernel: 19 pages swap cached May 25 03:09:01 vps1 syslogd 1.4.1: restart.
Because PHP doesn't give any feedback on why my swap space is filling up I don't know whether it's a server configuration problem or a faulty plugin or a wordpress problem.
Anyone any ideas?