Stopping gearman workers nicely

Solution 1

Generally I run my workers with the unix daemon utility with the -r flag and let them expire after one job. Your script will end gracefully after each iteration and daemon will restart automatically.

Your workers will be stale for one job but that may not be as big a deal to you as losing data

This solution also has the advantage of freeing up memory. You may run into problems with memory if you're doing large jobs as PHP pre 5.3 has god awful GC.

Solution 2

You could also add a quit function to all of your workers that exits the script. When you'd like to restart you simply give gearman calls to quit with a high priority.

function AutoRestart() {   static $startTime = time();   if (filemtime(__FILE__) > $startTime) {      exit();   }}AutoRestart();  

Well, I posted this question, now I think I have found a good answer to it.

If you look in the code for Net_Gearman_Worker, you'll find that in the work loop, the function stopWork is monitored, and if it returns true, it exits the function.

I did the following:
Using memcache, I created a cached value, gearman_restarttime, and I use a separate script to set that to the current timestamp whenever I update the site. (I used Memcache, but this could be stored anywhere--a database, a file, or anything).

I extended the Worker class to be, essentially, Net_Gearman_Worker_Foo, and had all of my workers instantiate that. In the Foo class, I overrode the stopWork function to do the following: first, it checks gearman_restarttime; the first time through, it saves the value in a global variable. From then on, each time through, it compares the cached value to the global. If it has changed, the stopWork returns true, and the worker quits. A cron checks every minute to see if each worker is still running, and restarts any worker that has quit.

It may be worth putting a timer in stopWork as well, and checking the cache only once every x minutes. In our case, Memcache is fast enough that checking the value each time doesn't seem to be a problem, but if you are using some other system to store off the current timestamp, checking less often would be better.