When I did the upgrade of concourse from 3.4.0 to 3.5.0, suddenly all running jobs changed their state from running to errored. I can see the string 'no workers' appearing at the start of their log now. Starting the jobs manually or triggered by the next changes didn't have any problem.
The upgrade of concourse itself was successful.
I was watching what bosh did at the time and I saw this change of job states took place all at once while either the web or the db VM was upgraded (I don't know which one). I am pretty sure that the worker VMs were not touched yet by bosh.
Is there a way to avoid this behavior?
We have one db, one web VM and six workers.
With only one web VM it's possible that it was out of service for long enough that all workers expired. Workers continuously heartbeat and if they miss two heartbeats (which takes 1 minute by default) they'll stall. They should come back after the deploy is finished but if scheduling happened before they heartbeats, that would cause those errors.
I have a node app in bluemix which holds some transaction cache in memory and I would like to flush this cache to DB before the application goes down. So I have the appropriate event handlers to intercept SIGTERM/SIGINT signals and all works fine from my laptop, however, it seems like the cf stop command does not perform graceful shutdown.
Unfortunately, there is no clear documentation around this topic, at one place in the cloudfoundary app-lifecycle doc they do mention that first SIGTERM is issued and then wait for 10 secs etc but Im not seeing this happening. Probably a bug on their side. https://docs.cloudfoundry.org/devguide/deploy-apps/app-lifecycle.html
Has anyone noticed this issue and probably have a workaround pls?
CF is sending the SIGTERM first but because of how the app is started by other processes, it's not being correctly propagated to your app.
As a workaround, disable App Management by setting the CF environment variable BLUEMIX_APP_MGMT_INSTALL=false and prefix your app's start command in your package.json file with 'exec' (e.g. exec node app.js).
I want to implement a automatic service restarting for several tomcat applications, applications that do take a lot of time to start, even over 10 minutes.
Mainly the test would check if the application is responding on HTTP with a valid response.
Still, this is not the problem, the problem is how to prevent this uptime check to fail while the service is under maintenance, scheduled or not.
I don't want for this service to be started if it was stopped manually, with `service appname stop".
I considered creating .maintenance files on stop or restart actions of the daemon and checking for them before triggering an automated restart.
So far the only problem that I wasn't able to properly solve was, how to detect that the app finished starting up and remove the .maintenance file, so the automatic restart would work properly.
Note, an init.d script is not supposed to wait, so the daemon should start a background command that solves this problem.
I'm dealing with a very strange problem now.
Since I queue the jobs over 1,000 at once, Gearman doesn't work properly so far...
The problem is that, when I reserve the jobs in background mode, I could see the jobs were correctly queued from the monitoring page (gearman monitor),
but It is drained right after without delivering it to the worker. (within a few seconds)
After all, the jobs never be executed by the worker, just disappeared from the queue (job server).
So I tried rebooting the server entirely, and reinstall gearman as well as php library. (I'm using 1 CentOS, 1 Ubuntu with PHP gearman library, and version is 0.34 and 1.0.2)
But no luck yet... Job server just misbehaving as I explained in aobve.
What should I do for now?
Can I check the workers state, or see and monitor the whole process from queueing the jobs to the delivering to the worker?
When I tried gearmand with a option like: 'gearmand -vvvv' It never print anything on the screen while I register worker to the server, and run a job with client code (PHP)
Any comment will be appreciated.
For your information, I'm not considering persistent queue using MySQL or SQLite for now, because it sometimes occurs performance issue with slow execution.
How have you set-up one or more worker scripts for queue-oriented systems?
How do you arrange to startup - and restart if necessary - worker scripts as required? (I'm thinking about such tools as init.d/, Ruby-based 'god', DJB's Daemontools, etc, etc)
I'm developing an asynchronous queue/worker system, in this case using PHP & BeanstalkdD (though the actual language and daemon isn't important). The tasks themselves are not too hard - encoding an array with the commands and parameters into JSON for transport through the Beanstalkd daemon, picking them up in a worker script to action them as required.
There are a number of other similar queue/worker setups out there, such as Starling, Gearman, Amazon's SQS and other more 'enterprise' oriented systems like IBM's MQ and RabbitMQ. If you run something like Gearman, or SQS - how do you start and control the worker pool? The questions is on the initial worker startup, and then being able to add additional extra workers, shutting them down at will (though I can send a message through the queue to shut them down - as long as some 'watcher' won't automatically restart them). This is not a PHP problem, it's about straight Unix processes of setting up one or more processes to run on startup, or adding more workers to the pool.
A bash script to loop a script is already in place - this calls the PHP script which then collects and runs tasks from the queue, occasionally exiting to be able to clean itself up (it can also pause a few seconds on failure, or via a planned event). This works fine, and building the worker processes on top of that won't be very hard at all.
Getting a good worker controller system is about flexibility, starting one or two automatically on a machine start, and being able to add a couple more from the command line when the queue is busy, shutting down the extras when no longer required.
I've been helping a friend who's working on a project that involves a Gearman-based queue that will dispatch various asynchronous jobs to various PHP and C daemons on a pool of several servers.
The workers have been designed to behave just like classic unix/linux daemons, thanks to simple shell scripts in /etc/init.d/, and commands like :
invoke-rc.d myWorker start|stop|restart|reload
This mechanism is simple and efficient. And as it relies on standard linux features, even people with a limited knowledge of your app can launch a daemon or stop one, if they know how it's called system-wise (aka "myWorker" in the above example).
Another advantage of this mechanism is it makes your workers pool management easy as well. You could have 10 daemons on your machine (myWorker1, myWorker2, ...) and have a "worker manager" start or stop them depending on the queue length. And as these commands can be run through ssh, you can easily manage several servers.
This solution may sound cheap, but if you build it with well-coded daemons and reliable management scripts, I don't see why it would be less efficient than big-bucks solutions, for any average (as in "non critical") project.
Real message queuing middleware like WebSphere MQ or MSMQ offer "triggers" where a service that is part of the MQM will start a worker when new messages are placed into a queue.
AFAIK, no "web service" queuing system can do that, by the nature of the beast. However I have only looked hard at SQS. There you have to poll the queue, and in Amazon's case overly eager polling is going to cost you some real $$.
I've recently been working on such a tool. It's not entirely finished (thought it should take more than a few more days before I hit something I could call 1.0) and clearly not ready for production yet, but the important part are already coded. Anybody can have a look at the code here: https://gitorious.org/workers_pool.
Supervisor is a good monitor tool. It includes a web UI where you can monitor and manage workers.
Here is a simple config file for a worker.
[program:demo]
command=php worker.php ; php command to run worker file
numprocs=2 ; number of processes
process_name=%(program_name)s_%(process_num)03d ; unique name for each process if numprocs > 1
directory=/var/www/demo/ ; directory containing worker file
stdout_logfile=/var/www/demo/worker.log ; log file location
autostart=true ; auto start program when supervisor starts
autorestart=true ; auto restart program if it exits