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[Plugin: W3 Total Cache] Huge CPU load (8 posts)

  1. cortex123
    Member
    Posted 4 years ago #

    I decided to give a shot with W3, since Super Cache wasn't working at 100%. But I will probably roll back to Super Cache since with W3 I have a huge CPU usage. Right now I've emptied the cache and CPU load took a peek at 128%!!!!!!!

    The website is also slow, and I'm confused on how everyone recommends W3, what's wrong on my side?

    Here's my VPS server specs:

    150 GB Storage (15K RPM SAS Drives)
    6 TB Monthly Transfer
    8 GB Guaranteed (16 GB Burst RAM)
    2 CPU Cores Guaranteed (Burst to 8 Cores)
    Hardware RAID 10
    CentOS 5 Operating System

    I'm using disk (enhanced).
    Any advices? :(

    http://wordpress.org/extend/plugins/w3-total-cache/

  2. Frederick Townes
    Member
    Posted 4 years ago #

    There's not enough information to guess. You can submit a bug submission form from the support tab of the plugin so I can see your setting and server info.

  3. cortex123
    Member
    Posted 4 years ago #

    Thanks for your reply, I have to go back on what I said.

    The thing is that I've used W3 while I was being hit by a huge amount of traffic. The server at that time was already at 20% or so, with W3 the server load went to unimaginable numbers like 300%. The server just couldn't handle. So what I did was stop the server account completly, and server load dropped almost down to 0%. Then I restart it with W3, and since then what I've heard has been true. It does a good joob indeed, altough I still have some server load that I wanted to get decreased. And I do think that W3 can do that job.

    So these are some of the issues that I want you to clarify if possible:

    1) I've seen that emptying cache on server peek hours might be self-suicide, I did it and it went to 500% (no j/k, it really happened), so I think that it was my fault there, or am I wrong? We can empty cache whenever and we wont notice server loads?

    2) Another thing is that since my site has something like 100,000 views/ days is pretty possible that when pages are cached or re-cached they start caching and auto-cleaning at the same time. It means that with 5,000 users online is pretty possible that we have 25% of the website caching and cleaning at the same time, what equals again to huge server load. I mean if cache for page A, B, C and D starts at 1pm, they will also be cleaned and re-cached at the same time, right? Or are there different expire times for each visitor?

    3) For dedicated servers do you recommend the opcode option? Or you always recommend disk (enhanced)? I'm asking this because I'm thinking on moving this website to a dedicated machine (Quad Core Xeon® X3460 Processor,4 x 2.8 GHz HyperThreaded Cores,8 MB L3 Cache, 1333 MHz FSB,16 GB 1333MHz DDR3 Memory,Serial ATA Storage in RAID 1) so the default settings are also the same for this kind of dedicated?

    4) Since DB is my main issue, do you suggest an higher number than 180 for Maximum lifetime of cache objects and more than 3600 for Garbage collection interval (both in the dedicated)?

    Sorry for the multiple questions, but now that I'm really digging W3 I want to know how to take the most out of it. Thanks alot!

  4. Frederick Townes
    Member
    Posted 4 years ago #

    I've seen that emptying cache on server peek hours might be self-suicide, I did it and it went to 500% (no j/k, it really happened), so I think that it was my fault there, or am I wrong? We can empty cache whenever and we wont notice server loads?

    No you definitely can't. It depends on your hardware, settings etc. It's better to set the expiration time low for pages if need be, otherwise caches will updated when new comments are posted or posts are edited.

    Another thing is that since my site has something like 100,000 views/ days is pretty possible that when pages are cached or re-cached they start caching and auto-cleaning at the same time. It means that with 5,000 users online is pretty possible that we have 25% of the website caching and cleaning at the same time, what equals again to huge server load. I mean if cache for page A, B, C and D starts at 1pm, they will also be cleaned and re-cached at the same time, right? Or are there different expire times for each visitor?

    "Huge amount" is relative to your server specifications + theme. Database caching with an opcode cache will reduce your page generation time best. More features for this type of case are coming soon. Expire times are not per visitor they're per page. W3TC tries to make sure that browser cache pages very well also. If users are posting comments, there's only so much that page caching can do for you (until the next release).

    For dedicated servers do you recommend the opcode option? Or you always recommend disk (enhanced)? I'm asking this because I'm thinking on moving this website to a dedicated machine (Quad Core Xeon® X3460 Processor,4 x 2.8 GHz HyperThreaded Cores,8 MB L3 Cache, 1333 MHz FSB,16 GB 1333MHz DDR3 Memory,Serial ATA Storage in RAID 1) so the default settings are also the same for this kind of dedicated?

    To be honest those server specs do not mean much to me. Your theme and traffic pattern is what will determine if that hardware is sufficient. RAID 1 is not good for MySQL btw, RAID 10 is better. There are countless apache, PHP and MySQL tricks that can make a difference here. But disk enhanced is best for a standalone server. Use an opcode cache for database caching. And disk for minify. Get a CDN like http://MaxCDN.com and use Mirror method.

    Since DB is my main issue, do you suggest an higher number than 180 for Maximum lifetime of cache objects and more than 3600 for Garbage collection interval (both in the dedicated)?

    Unfortunately everyone thinks that giving so many options means they have to be changed, what they're really for is dealing with problems if they exist.

    To answer your question, don't change these settings unless you can determine that doing so will alleviate a problem. There are no hard and fast answers for these questions, there are too many factors and I don't even know you're domain name. :)

  5. cortex123
    Member
    Posted 4 years ago #

    Sorry for the late reply frederick.

    I really appreciate the way you support your plugin, is kinda rare to see a plugin author replying to questions in just a couple of hours. So thumbs up for your support.

    I normally dont post my url's on public forums, but again I'm impressed with your support.

    Just one last question:

    Comments seem to be a huge factor for W3 setting, in my case, I've disabled comments, interaction with users is only done with postratings and post views, do you have any special setting for websites with no comments and only a few options for users like mine?

  6. Frederick Townes
    Member
    Posted 4 years ago #

    Comments seem to be a huge factor for W3 setting, in my case, I've disabled comments, interaction with users is only done with postratings and post views, do you have any special setting for websites with no comments and only a few options for users like mine?

    I'm not sure I'm clear on the point. You want to know if there are additional performance improvements available for sites that don't use comments?

  7. cortex123
    Member
    Posted 4 years ago #

    Exactly. Since comments are so dynamic, you probably have a setting for less dynamic blogs, if you know what I mean.

  8. Frederick Townes
    Member
    Posted 4 years ago #

    No, if you don't have comments, then nothing needs to change. Your server will have more resources for generating caches compared to a site with frequent comments. If you really want you can increase the expiry time for your pages, but that's not always necessary for a given site, so I cannot speculate.

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