I'm using below cmd to get data from remote server using SSH in perl : 

 my $o = `ssh  -n -x -q -o StrictHostKeyChecking=no -o BatchMode=yes -
+o ConnectTimeout=5 host /script 2>/dev/null`;
<code>

<p> then, I process the $o and print to STDOUT .

Now, the problem here is, when the data returned by the ssh is huge, t
+hen, the perl program hangs forever.

I did truss of the process id, it shows output like 
</p>

<c>
 read(3, 0x001DF90C, 5120)                       = 5120
 ---chunk of data from remote host ---
 brk(0x001E2470)                                 = 0
 brk(0x001E2470)                                 = 0
 brk(0x001E4470)                                 = 0
 read(3, 0x001DF90C, 5120)                       = 5120
 ---chunk of data from remote host ---
 ---above continues until all data from rhost is read ---
 ---then starts write operation :
 write(4, 0x00229D64, 5120)                      = 5120
 ---writes chunk of data read from rhost
 ---does for some more chunks then hangs forever---
  write(4, 0x00229D64, 5120)      (sleeping...)

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I also found out that the ssh process created by the perl program is not hanging.
Is there problem in storing huge data into a variable (memory) in perl ? Here's the ulimit of the system : 

time(seconds)        unlimited
file(blocks)         unlimited
data(kbytes)         unlimited
stack(kbytes)        8192
coredump(blocks)     unlimited
nofiles(descriptors) 4096
vmemory(kbytes)      unlimited

[download]

Need your help in sorting the problem.

In reply to perl hangs on write syscall by Anonymous Monk

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