Ok, thanks for the clarification :-) I guess an opcode cache server of some sort would be the only way to do this, listening either on a Unix socket og a TCP/IP socket. Probably not worth it anyway.
I'm going to leave the list again as I just wanted to share my "brilliant" idea with you guys :-) Cheers, Mikael man. 2. maj 2016 kl. 11.45 skrev Joe Watkins <pthre...@pthreads.org>: > Morning Mikeal, > > The memory that opcache uses is anonymously mapped shared memory, this > cannot be shared across distinct processes, it is not backed by any file. > > Even if you were to back the memory with a file, the most efficient > synchronization primitives that exists cannot be shared across distinct > processes either. > > This is why opcache, apc(u) etc only work as expected in a prefork > multi processing model. > > Cheers > Joe > > On Sun, May 1, 2016 at 11:12 PM, Mikael Lyngvig <mik...@lyngvig.org> > wrote: > >> Hi guys, >> >> I am working on and off on my own programming language, but knowing myself >> well, I know that this is just a hobby project that will never be >> finished. >> >> I have an idea for PHP7 that may or may not be relevant to you guys. I do >> code in C but I don't have the time to get deeply involved in PHP. >> Therefore I will present my idea. I hope that your reply will be "Oh, >> PHP(x) already does this!" or "Great, that sounds useful to us!" :-) >> >> The idea is especially relevant to large web hosting companies that run >> tens of thousands of PHP-powered websites. It has only little relevance >> to >> a small VPS running few pages. >> >> The basic idea is as follows: >> >> Try to reduce the global memory load on the PHP opcode cache and the >> server >> by sharing cached module's opcodes across totally independent sites on the >> server. >> >> I know this has to be done very carefully, otherwise all hell will break >> lose :-) >> >> My take on this idea is this: >> >> 1. Compute an SHA512 checksum for all source files that are entered into >> the opcode cache. >> 2. If the SHA512 checksum is identical to an existing checksum, the files >> are considered identical and can share entries in the opcode cache (which >> needs a reference count or something). >> 3. To reduce the overhead of computing the SHA512 checksum, the SHA512 >> checksums are cached in another cache. >> 4. This makes for two caches: the checksum cache and the opcode cache >> (called "the module cache" below). >> >> The first cache, the checksum cache, is updated whenever a new PHP source >> file needs to be cached. >> The second cache, the opcode cache, is ONLY updated if the checksum is not >> already in the checksum cache. >> >> The idea here is that PHPx can cache opcodes from, say, 200 different >> WordPress installations (of the exact same version, although this happens >> automatically) as ONE opcode cache entry. This should really be a nice >> gift to all the great web hosting companies out there that offer PHPx as >> part of their service. Suddenly their machines may have 200-1000 times "as >> much" opcode memory as before. >> >> I hope this makes you happier not unhappier! If my idea is crazy or >> cannot >> be done for reasons I don't see, please let me know. I just think it is a >> cool idea and it is a shame that it lies unused on my harddisk when you >> might as well make use of it. I use PHP daily and I so much look forward >> to my web hosting company upgrading to PHP7 because of the default >> exception error reporting and the enhanced opcode cache. >> >> P.S. The sample code is written in my own language, but should be readable >> to virtually anybody. >> >> Cheers, >> Archfrog >> >> My private notes (in case they help somebody understand what I mean) are: >> >> A source file contains a single module, which may contain definitions >> for any number of symbols. The source file is cached using >> its SHA-512 value so that multiple identical source files in the >> system are treated as one. This saves a lot of space in shared >> hosting environments where the same source files (WordPress, etc.) are >> located in thousands of locations on the disk. Instead of >> keeping thousands of redundant copies in memory, this system only >> keeps a single copy. The location of the source mode has no >> influence on how it is cached, unlike in traditional systems, and the >> date-time value of the file is also ignored due to the fact >> that many hosting environments only allow FTP access, which is not >> generally guaranteed to preserve the time stamp of files during >> uploaded. >> >> To simplify things, the system mandates that any and all source files >> can fit into available memory. Large source files, of >> gigabytes in size, are thus not supported, which really shouldn't be a >> problem in real life. >> >> This design makes use of a two-level cache: >> 1. The first cache is the SHA-512 cache, which maps a ( path, time, >> data ) triplet into an SHA-512 value in such a way that the >> data block is not read from disk unless the path+time is missing in >> > the cache, in which case the cache item is recomputed.2. The second > > >> cache is the module cache, which maps an SHA-512 value into a >> ready-to-use module (a sequence of opcodes). >> >> These two caches together are expected to eliminate 90+ percent of all >> checksum calculations and source file compilation >> operations. >> >> When a new source file needs to processed, the driver performs the >> following steps: >> # Create new 'File' object containing the data (lazily loaded), >> path, size, and time of the file. create file := new >> Braceless0.Platform.Disk.File(path) >> # Try to retrieve the checksum value from the checksum cache, >> otherwise compute it and update the checksum cache. create checksum >> is SHA512 if not checksums.Lookup(file.Path, file.Time, out >> checksum): let checksum := new Checksum(file.Data) call >> checksums.Insert(file.Path, file.Time, checksum) >> # Try to retrieve the compiled wordcode from the scripts cache, >> otherwise compile it and update the scripts cache. create script is >> Script if not scripts.Lookup(checksum, out script): let >> script := new Script(file) call scripts.Insert(checksum, >> script) >> >
