Windows hangs and High CPU¶

Known issues to check first¶

Hang (partial startup) on Windows with SSL enabled

IBM HTTP Server 7.0 and earlier automatically probes for legacy (IP-connected) cryptographic accelerators. If you encounter a hang during startup on Windows, try adding SSLAcceleratorDisable to each VirtualHost with SSL enabled.

This directive is separate from modern crypto cards configured with SSLPKCSDriver.

System preparation¶

If you have not previously setup the Windows error reporting tools to save error information then refer to 'MustGather setup of error reporting dump tools for Microsoft Windows' for information on performing this setup. This setup step must be performed prior to recreating the hang. Make sure you are aware of the directory into which the tool will save the log and dump data.

Remove any existing Windows log and crash files from its output directory (after backing up as appropriate).

Also, please ensure that 'ExtendedStatus On' is enabled in the web server configuration file.

Install ProcDump from Microsoft Windows Sysinternals to request dumps from hung processes.
Add the Procdump install location to your Path or make a note of the install location so that you can invoke the utility from that location later. Note that the Procdump install zip contains both a procdump.exe and a procdump64.exe (for 64-bit OS systems)

AFPA¶

AFPA must be disabled and IBM HTTP Server restarted in order to collect some of the information below. You must be aware of whether or not AFPA is enabled in the web server configuration file before gathering the hang information. We recommend that AFPA be disabled in advance if the hang is reproducible so that the best set of information is available for analysis. To ensure that AFPA is disabled verify that the LoadModule statement for mod_afpa_cache.so in the configuration file is either commented out or absent, i.e.:
#LoadModule ibm_afpa_module modules/mod_afpa_cache.so
This module is no longer shipped with IHS starting with Version 9.0.

Obtaining information at the time of the hang or issue¶

These steps must be performed at the time of the hang

Gather general system and web server information.

This information is gathered by running the ihsdiag ServerDoc DescribeConfig tool as described by the instructions in the System and web server information tool documentation.
This will result in a directory of information named 'ServerConfig.timestamp'.
That directory should be zipped and sent to IBM using the provided instructions after completing the following steps for obtaining additional information.
TCP connection information

Run 'netstat -an > netstat.txt' at a command-prompt.
Save the netstat.txt file into the 'ServerConfig.timestamp' directory.
Network configuration

Run 'ipconfig /all > ipconfig.txt' at a command-prompt.
Save the ipconfig.txt file into the 'ServerConfig.timestamp' directory.
Server status report

('ExtendedStatus On' must be enabled for the running web server.)

From a web browser, request http://www.example.com/server-status/?showmodule from a web browser.
(Replace www.example.com with your web server address). If the web server is completely hung, it may not respond. Otherwise, save the server status report as a file in the 'ServerConfig.timestamp' directory.
Task Manager information
- Windows 2012 or newer
  - Start 'Task Manager' (You can run 'taskmgr.exe' from a Command Prompt)
  - Select the 'Details' tab
  - Make sure the needed columns are displayed
    - At a minimum, the following columns of information should be displayed:
      - PID
      - User name
      - CPU
      - CPU Time
      - Working set (memory)
      - Memory (private working set)
      - Handles
      - Threads
      - User objects
      - I/O read bytes
    - To select columns to be displayed:
      - Right-click one of the column headers (such as 'Name')
      - Click 'Select columns' on the menu that is displayed
        (A 'Select columns' window is displayed)
      - Select the checkbox of each column to be displayed (Refer to the list above)
      - Click the 'OK' button to save the settings
  - Click the 'Name' column header to sort the list of processes by name.
- Windows versions prior to Windows 2012
  - Start 'Task Manager' (You can run 'taskmgr.exe' from a Command Prompt)
  - Select the 'Processes' tab
  - Make sure the needed columns are displayed
    - At a minimum, the following columns of information should be displayed:
      - PID (Process Identifier)
      - CPU Usage
      - CPU Time
      - Memory usage (Memory - Private Working Set)
      - USER Objects
      - I/O Read Bytes
      - User Name
      - Handle Count (Handles)
      - Thread Count (Threads)
    - To select columns to be displayed:
      - Select 'View / Select Columns...'
        (A 'Select Columns' window similar to the following is displayed):
      - Select the checkbox of each column to be displayed (Refer to the list above)
      - Click the 'OK' button to save the settings
    - Select the 'Show processes from all users' checkbox on the Processes tab page (if not already selected)
    - Click the 'Image Name' column header to sort the list of processes by name.
  - For all Windows verisons after following the appropriate steps above:
    
    Find the two Apache.exe or httpd.exe processes.
    
    The process with the larger number of threads (252 threads in the example above) is the IHS child process. (Note: This should be almost the value set for ThreadsPerChild in the config). Make a note of the associated PID (2292 in the example above) for the IHS child process. It will be used later.
    Note: The child PID can also usually be determined by looking for the IHS process with +/- ThreadsPerChild number of threads displayed in the output of a 'pslist' invocation.
    
    With the Task Manager window selected, press <Alt><PrtSc> to save an image of the window to the clipboard.
    
    Run the Windows Wordpad program and paste the image of the Task Manager window into the new file. Save it as taskmgr.doc or taskmgr.rtf.
    Copy the saved file into the 'ServerConfig.timestamp' directory.
Web server state - capture a dump

You must skip this step if AFPA is enabled, which is why it is important to have disabled it as described earlier in this document.

Choose one of the following techniques to capture a dump:
- Use Procdump tool (preferred):
  
  Run 'procdump64 -ma CHILDPID' [Use 'procdump' for 32-bit OS systems.]
  (where CHILDPID is the PID of the IHS child process as determined in the prior steps above.)
  
  Note the location of the dump as printed in your command prompt window. Copy the file(s) into the 'ServerConfig.timestamp' directory.
  
  Note: Multiple invocations will create uniquely named dumps and does not overwrite previously generated dumps until the DumpCount value is reached (default is 10) at which point the older dump files will be overwritten as new dumps are created. {DumpCount an be adjusted under the LocalDumps registry entry. If needed, refer back to 'MustGather setup of error reporting dump tools for Microsoft Windows' }
- Use Dr.Watson tool (an option only for OS versions prior to Windows 2008):
  
  Run 'DRWTSN32.EXE -p CHILDPID' to create Dr.Watson log and crash files representing the current state of the web server.
  (where CHILDPID is the PID of the IHS child process as determined in the prior steps above.)
  
  If a dialog box appears stating that an error log is being created, don't press Cancel. Instead, wait for the text of the button to change to OK. Then press OK.
  
  The Dr. Watson files can now be found in the output locations configured in the DRWTSN32.EXE program, as described above under System preparation. Example:
```
          C:\DrWatson_dumps>dir
           Volume in drive C is C_Drive
           Volume Serial Number is 98E7-6D3C

           Directory of C:\DrWatson_dumps

          08/05/2009  09:32a      <DIR>          .
          08/05/2009  09:32a      <DIR>
          04/05/2010  03:48p           1,118,951 drwtsn32.log
          04/05/2010  03:49p          12,969,444 user.dmp
                         2 File(s)     14,088,395 bytes
                         2 Dir(s)  18,162,450,432 bytes free
```
  The files drwtsn32.log and user.dmp are the files to save.
  Copy the files into the 'ServerConfig.timestamp' directory.
Any additional error or access log files that might be available.

The access.log and error.log files will be automatically gathered by the ServerDoc DescribeConfig tool used above, but if the configuration file has been changed to specify differently named log files then you should copy these log files from the IHS_install_root\logs\ directory to the 'ServerConfig.timestamp\files\logs' directory.
WebSphere plug-in trace file

The actual location is specified in plugin-cfg.xml and is generated by configuring LogLevel="Trace".
Example: c:\WebSphere\AppServer\logs\http_plugin.log
Copy the file into the 'ServerConfig.timestamp' directory.
Event Viewer information
- Open the 'Event Viewer' (All Programs / Administrative Tools / Event Viewer)
- For both the 'Application' and 'System' logs:
  - Select the log in the tree
  - Rt-click and select 'Save Log File As...'
  - Name each file the same as the log (i.e. 'Application' or 'System'), and select a type of 'Event Log (*.evt)'
  - 'Save' into the 'ServerConfig.timestamp' directory
    (the directory created in the first step by running 'ServerDoc DescribeConfig')

Recap of information to send to IBM support:¶

Create a zip file of the 'ServerConfig.timestamp' directory as described in the System and web server information tool documentation. Send this ServerConfig.timestamp.zip containing the following to IBM support for analysis:

IHS information gathered by the 'ServerDoc DescribeConfig'
TCP connection information, as saved to file netstat.txt
Network configuration, as saved to file ipconfig.txt
Server status report, if it could be loaded
Task manager information, as saved to taskmgr.doc or taskmgr.rtf
Web server state, as represented by the dump and log file(s) (If AFPA is disabled)
All error and access logs
WebSphere plug-in trace file
Event Viewer export files

Instructions to send diagnostic information to IBM support.