On Wed, Nov 23, 2011 at 01:25:09PM +0200, goran kent wrote:

As we move away from blocking i/o, we need to manage buffers manually and be prepared for partial success. (Eventually we need to deal with timeouts and failovers, because otherwise the system remains vulnerable to its weakest link and hangs when a single node goes down -- but that's for later.)

Those confess() calls are placeholders, to be swapped out at some future time with a less aggressive error reporting mechanism that does not take down the server process. The idea was to use confess() during early rapid prototyping to flag each place a system call return value needs to be checked.

In some cases, including here, the code also needs to be refactored around non-blocking i/o. What we ultimately need to do is accept a partial read, store the incomplete buffer, and return to waiting for the next ready socket. The code will become more complicated because we'll have to keep multiple buffers alive, but that's concurrency for ya.

For now though, try this:

* Change every sysread() to read(), and every syswrite() to write(). * Set $socket->autoflush(1); * Make sure 'Blocking => 0' is commented out. * Replace the select() loop with a "for" loop, because select() and blocking i/o don't mix.

What I'm hoping to do with those changes is return to forcing every socket communication to block, restoring predictable program execution order.