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ECJ-INTEREST-L  June 2014

ECJ-INTEREST-L June 2014

Subject:

Re: Slaves don't always shut down, experiment hangs

From:

Sean Luke <[log in to unmask]>

Reply-To:

ECJ Evolutionary Computation Toolkit <[log in to unmask]>

Date:

Fri, 6 Jun 2014 08:26:05 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (102 lines)

The protocol for shutting down is that when the master wants to quit, either because it (1) was told by a slave that it found the optimal individual or (2) it ran out of time, it then sends a signal to each of the slaves. When a slave receives this signal, it's supposed to quit. The master waits for all the slaves to quit, then it dies.

This means that the bug could be in one of two places
- The master isn't sending a slave the signal
- The slave received the signal but isn't quitting

Your analysis suggests it's the first, but that seems unlikely. I need you to do some printing on the slave side -- or a dump to the slave statistics file -- which indicates that the slave did in fact receive the signal.

As to the FATAL ERROR. This error happens when the master breaks connection with the slave, which only happens when the master is quitting. The slave then quits as a result due to the exceptional condition. Now this is a deeper mystery because you said that the master *isn't* quitting; and furthermore the only other possibility is that the master has closed the connection because it knows the slave is quitting... but that's not happening.

I need a code example. Can you provide me one personally?

Sean

On Jun 6, 2014, at 12:47 AM, Eric 'Siggy' Scott <[log in to unmask]> wrote:

> PS: I've confirmed that this also occurs with SimpleEvolutionState, not just SteadyStateEvolutionState, so it has nothing to do with asynchronous evolution proper.
>
>
> On Fri, Jun 6, 2014 at 12:35 AM, Eric 'Siggy' Scott <[log in to unmask]> wrote:
> I'm running asynchronous evolution with the latest SVN revision. This is a toy experiment, so all my slaves are running on the same machine as the master.
>
> All the slaves are supposed to shut themselves down at the end of the run upon a command from the master (in non-daemon mode), or keep purring in the background (in daemon mode).
>
> What I see, however, is that in both cases a handful of slaves shut down, and handful do not, and then the master hangs.
>
> For instance, the following is a case where I have 10 slaves running in daemon mode, and master executing multiple jobs in sequence. Job 0 ran fine -- I got 10 "connected successfully" messages at the beginning and 10 "shut down" messages at the end. But here is the output of job 1:
>
> Threads: breed/1 eval/1
> Seed: 1869276809
> Job: 1
> Setting up
> WARNING:
> You've chosen to use Steady-State Evolution, but your statistics does not implement the SteadyStateStatisticsForm.
> PARAMETER: stat.child.0
> Initializing Generation 0
> Slave /127.0.0.1/1402028546585 connected successfully.
> Slave /127.0.0.1/1402028546798 connected successfully.
> Slave /127.0.0.1/1402028546699 connected successfully.
> Slave /127.0.0.1/1402028546658 connected successfully.
> Slave /127.0.0.1/1402028546690 connected successfully.
> Slave /127.0.0.1/1402028546773 connected successfully.
> Slave /127.0.0.1/1402028546763 connected successfully.
> Slave /127.0.0.1/1402028546753 connected successfully.
> Slave /127.0.0.1/1402028546794 connected successfully.
> Slave /127.0.0.1/1402028546755 connected successfully.
> Generation 1 Evaluations 50
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 2 Evaluations 100
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 3 Evaluations 150
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 4 Evaluations 200
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 5 Evaluations 250
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 6 Evaluations 300
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 7 Evaluations 350
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 8 Evaluations 400
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 9 Evaluations 450
> Subpop 0 best fitness of generation Fitness: 1.0
> Generation 10 Evaluations 500
> Subpop 0 best fitness of generation Fitness: 1.0
> Subpop 0 best fitness of run: Fitness: 1.0
> Slave /127.0.0.1/1402028546585 shut down.
> Slave /127.0.0.1/1402028546798 shut down.
> Slave /127.0.0.1/1402028546699 shut down.
> Slave /127.0.0.1/1402028546658 shut down.
> Slave /127.0.0.1/1402028546690 shut down.
>
> After shutting down a fraction of the slaves, it hangs. I have to control-C to exit.
>
> The failure appears to be random -- sometimes it occurs at the end of the 0th job. It still occurs when the slaves are launched in non-daemon mode. Sometimes the failure does not show up until the 4th or 5th job. The number of slaves that succeed or fail to shut down appears to be arbitrary. In short, we have all the signs of a race condition.
>
> When there is a failure, some of the slaves (but not necessarily the same number of slaves that succeeded or failed to shut down) print the message:
>
> FATAL ERROR:
> Unable to read individual from master.java.net.SocketException: Broken pipe
>
> I ran a debugger on a non-daemon slave that failed to shut down -- it seemed to be stuck happily waiting to receive a message from the master, as if it'd never been told to shut down at all.
>
> Besides that, I don't know what's going on.
>
> Siggy
>
> --
>
> Ph.D student in Computer Science
> George Mason University
> http://mason.gmu.edu/~escott8/
>
>
>
> --
>
> Ph.D student in Computer Science
> George Mason University
> http://mason.gmu.edu/~escott8/

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