BufferedReader.readline() hangs

Question

I'm trying to run /usr/bin/perl -e 'for(my $i=0;$i<1000;$i++){print 1x1000;print STDERR 2x1000;}' (which works in terminal) with my program.

ProcessBuilder pb = new ProcessBuilder(go); //go is the command
process = pb.start();
BufferedReader incommandbuf = new BufferedReader(new InputStreamReader(process.getInputStream()),1024*1000);
BufferedReader errcommandbuf = new BufferedReader(new InputStreamReader(process.getErrorStream()),1024*1000);
stdString = "";

while ((line = incommandbuf.readLine()) != null)
{
    stdString += line + "\n";
}
String errorstrtemp = "";
while ((line = errcommandbuf.readLine()) != null)
{
    errorstrtemp += line + "\n";
}

If I try to run this it hangs on while ((line = incommandbuf.readLine()) != null) . The program runs if I change the command to /usr/bin/perl -e 'for(my $i=0;$i<64;$i++){print 1x1000;print STDERR 2x1000;}' . If it goes up to 65 and higher it doesn't work. At first I thought I just have to change the size of the my BufferedReaders but it didn't help. Any clue on what is causing this? I will provide any additional info if needed. Thanks.

Answer 1

You are reading one stream at a time. When the other stream fills up the buffer, your Process will stop waiting for you to read it. The solution is to either read the streams in different threads or use ProcessBuilder.redirectErrorStream