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Cisco Bug: CSCus77661 - Console connection lost when performing max open file stress test on WSA

Last Modified

Feb 14, 2018

Products (1)

  • Cisco Web Security Appliance

Known Affected Releases

8.5.0-497 8.6.0-018

Description (partial)

Symptom:
Loose console connection:  Get communication error (broken pipe).

Conditions:
Console connection is lost when running the max files open stress test on both HW WSA and virtual WSA.  Stress is accomplished by using up the resources by opening max number files.  Get "communication error: broken pipe" when using console.  Error "cannot open /lib/libkvm.so.5" is generated on existing SSH session.The same was tested on WSA on esxi and HW WSA.  When the resources are released (by killing process that open files), we regain console access and SSH connection.

Console connection is lost when running the max files open stress test on both HW WSA and virtual WSA.  Stress is accomplished by using up the resources by opening max number files.  Get "communication error: broken pipe" when using console.  Error "cannot open /lib/libkvm.so.5" is generated on existing SSH session.The same was tested on WSA on esxi and HW WSA.  When the resources are released (by killing process that open files), we regain console access and SSH connection.

Following is the procedure to recreate the issue: (excerpt from Test Plan EDCS-1457068)

To determine the system level value for max open files use the
pstat(8) command by copying it to the appliance.

Note: pstat(8) is dynamically linked, copy from qa box of the same BSD version as under test.

% scp /usr/sbin/pstat r<usrname>@<hostname>:
% ssh <hostname>
% ./pstat -T # 4.8.0 open/max files (all models);
286/16384 files

A python program to open files:

import os
import sys
import commands

def max_file_handles():
  file_handles = []
  while True:
    total_open_files = len(file_handles)
    try:
      file_handles.append(open("file_handle_%s"%(total_open_files,),'w'))
    except:
      print total_open_files
      #sys.exit()

if __name__ == "__main__":
    max_file_handles()

Open files in a repetitive loop until maximum is reached.  3 ssh sessions that run the same python script were opened to reach max files open.  We use pstat to monitor # of files opened.
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