Re: maintaining shared memory size (was: Re: swamped withconnection?)
On Wed, 2005-08-24 at 07:02 -0400, Sean Davis wrote: As an aside, are there rules of thumb about what cache works best in various situations? Cache::FastMmap and BerkeleyDB are the fastest by far, but they are local to one machine. Cache::Memcached or a simple key/value table in a MySQL server are second fastest, and can be shared between machines. After that, everything else is a lot slower. Some stats are available here: http://cpan.robm.fastmail.fm/cache_perf.html Are RDBMS's, if accessible, generally a good solution? For caching? MySQL is surprisingly fast when handling primary key requests against a simple table. It's faster than Cache::Cache and most of the other caching modules. - Perrin
Re: maintaining shared memory size (was: Re: swamped withconnection?)
On Tue, 2005-08-23 at 17:23 +1000, Badai Aqrandista wrote: How do I maintain the size of the shared memory between apache children? What cause a memory page to be copied (not shared) from perl's point of view? Anything that writes to memory -- modifying any variable (even just reading one in a different context) or compiling some code are the most common things. There's a bit more here: http://modperlbook.com/html/ch10_01.html Oh my, I should've kept memory consumption in mind when designing the code in the first place. Anyway, to fix this, I'm trying to make my onw shared memory with Apache::SharedMem. But it seems that shared memory is just a memory area that any process can read from or write to, not a memory that can become part of any process's memory space. I'd like to put the read only data in a memory area that can become part of any process's memory space, like threads sharing memory space. Is there any way I can do that? How about mmap? I have never looked into that. Does this sound like fixing the wrong problem? Thank you... --- Badai Aqrandista Cheepy (?) _ On the road to retirement? Check out MSN Life Events for advice on how to get there! http://lifeevents.msn.com/category.aspx?cid=Retirement
Re: maintaining shared memory size (was: Re: swamped withconnection?)
On Wed, 2005-08-24 at 10:31 +1000, Badai Aqrandista wrote: Anyway, to fix this, I'm trying to make my onw shared memory with Apache::SharedMem. Don't use that module. It's very inefficient. But it seems that shared memory is just a memory area that any process can read from or write to, not a memory that can become part of any process's memory space. I'd like to put the read only data in a memory area that can become part of any process's memory space, like threads sharing memory space. Is there any way I can do that? You can share read-only data by loading it into normal variables during startup. You can share read/write data by keeping it in a database (including things like BerkeleyDB or Cache::FastMmap) and only reading the small parts of it that you need in each process. There is no way to access data in perl without the size of the process you read the data from allocating memory to hold that data while you use it. In other words, shared memory is not useful for reducing the size of existing processes unless those processes are currently each holding a lot of data that they never use. Does this sound like fixing the wrong problem? Yes. Put a reverse proxy in front of your server, tune MaxClients so you won't go into swap, and then benchmark to see how much load you can handle. Then think about tuning. - Perrin
