”><xmp>TokuLog 改メ tokuhirom’s blog

■summary of cons/pros about ithreads/coro/fork(2)

rafl wishes gfuji and tokuhirom would blog in english

などといわれたので、ためしに英語で1エントリだけかいてみるよ。

Perl5 has some ways for concurrent programming.This article is research summary for that tools.

summary

detail

ithreads

• ithreads is a port of win32 process emulation for UNIX.
• ithreads uses a lot of memory
  • This cause swap out...
  • Cannot create a lot of threads
• ithreads' new thread creation is very slow
  • very very slow
• a lot of CPAN modules are not ithreads safe.
• ithreads enabled perl is makes 0.1x slower(see http://d.hatena.ne.jp/gfx/20090629/1246262660)
• Sharing variable between ithreads is never easy.
  • blessed objects, etc...
• ithreads dump core too often

fork(2)

• save memories by Copy on Write mechanism(on *nix systems)
• forked processes are very stable and CPAN friendly =)
• forked processes works on multiple CPUs.This is good for modern servers.
• Programming management forked processes is hard.
  • I don't want to fork Apache!
  • I hate zombie process...

Coro

• Coro is black magic.
• Coro's coroutine is very lightweight!
• Coro doesn't use a lot of memory.
• Programming with Coro is very easy.
• Very easy to communicate between coros.

Conclusion

• I don't want to use ithreads.
• fork(2) is good enough for most cases
  • CPU intensive problems should use fork(2)
• Coro is good for I/O intensive problems
  • like a crawler
• Coro is good for web applications
  • send a queries for RDBMS concurrently
  • Coro can pass the result of queries easily =)
  • etc.

ツイートする

Permalink | コメント(0) | トラックバック(0) | 10:08