Re: Suspended processes

You need to use a channel, and set it to non-blocking.  I haven't been
able to find the code I wrote, but look up
java.nio.channels.Pipe.


Sam Seaver wrote:

> I knew it was something like that!
>
> I just had a look at the NIO classes, and to be honest, i dont see where
> they fit in, it would be great to simply have non-blocking IO, but does
> anyone have an example of how I can have a non-blocking read of output
> and
> stderr?
>
> Thanks
> Sam
>
>
>
>
>>    I'm not sure but it I would guess at one of two issues:
>>
>>   1. You don't seem to be reading the output and stderr in the
>>      fragment.  You need to keep these channels moving, otherwise the
>>      process will hang trying to deliver output.  You could consider
>>      setting the IO to /dev/null (or NUL:) in the script so as to
>>      assure there is no output pending.
>>   2. If you do start reading from these, keep in mind that the
>>      container is usually in charge of managing threads.  Since most
>>      examples show creating threads to read and process the output,
>>      this may be a problem.  This is because the default read/write
>>      facilities don't support non-blocking IO, you need to use the NIO
>>      classes for that.
>>
>>
>>
>> Sam Seaver wrote:
>>
>>> I have a JSP web interface that runs a perl script natively using a
>>> bean:
>>>
>>> String[] cmd ={"/home/seaver/MONSTER/monster", "-i" + getJobID(),
>>> filePath +
>>> dir + getPdbFileName()};
>>>        try{
>>>            Process proc = Runtime.getRuntime().exec(cmd);
>>>            BufferedWriter output = new BufferedWriter(new
>>> OutputStreamWriter(proc.getOutputStream()));
>>>            BufferedReader input = new BufferedReader(new
>>> InputStreamReader(proc.getInputStream()));
>>>            BufferedReader error = new BufferedReader(new
>>> InputStreamReader(proc.getErrorStream()));
>>>        }catch (Throwable t){
>>>            t.printStackTrace();
>>>        }
>>>
>>> The program perl script, monster, runs fine natively, and it runs fine
>>> when
>>> activated from the web interface.
>>>
>>> The files passed into the web interface contains records which monster
>>> parses and then inputs into a small C program.  This all works fine,
>>> even
>>> with multiple records (leading to the one monster instance running
>>> the C
>>> program multiple times)
>>>
>>> however, if a file with multiple records is passed through the web
>>> interface, after doing the first few records, the perl script just
>>> simply
>>> suspends.  From the look of the output, it is almost as if it never
>>> recieves
>>> back a PID from the C program, and so it hangs.
>>>
>>> But this only happens when i run it via the web interface, so what is
>>> happening here!?
>>>
>>> S
>>>
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