Re: oncurrence problem with PEAR:MDB2 + msqli driver in forked CLI environment

On Thu, Jul 4, 2013 at 6:09 PM, Toni Moreno <toni.moreno@gmail.com> wrote: > Hi. > > I have a found a very strange and big "concurrence" problem after develop a > CLI tool which parallelizes data processing by using "pcntrl_fork", ( If > we run the same executions sequentially the result is correct) > > The trouble appears when some of the child processes die while trying to > access to DB , after child dies, parent process always get status code of > 1 or 255.. > > We can reproduce problem but error messages are not the same always ( I > attach 3 error log examples) > > It seems like a previously stablished connection exists to the bd before > forking and child processes are working all over it. > > Anybody can say me how can I force child processes to make their own new > connections to de BBDD ? > > > Lots of Thanks!! > > First of all, PHP is probably not the right language to do data processing, but that's up to you. Second, pcntl_fork is pretty experimental stuff, it's not very stable. Now to answer your question, it's hard to say without seeing the code, but I would suspect you only create the database connection once, and use it from all forks. The correct way is to create 1 connection per thread, so the threads will not interfere with each other. Hope this helps, if not, please show us a small example that demonstrates the problem. Regards, Matijn