Symptoms
Inventory is not successfully gathered from a computer running a Unix-like operating system. When inspecting the /var/opt/managesoft/log/tracker.log file, details like the following are observed.
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} ************************************************************
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} Program arguments are '/opt/managesoft/libexec/ndtrack -t Machine -o Upload=false'
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} Preferences loaded
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} Inventory Setting file is '/var/opt/managesoft/tracker/inventorysettings/InventorySettings.xml'
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} Obtaining semaphore lock (to ensure only one instance is running)...
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} ERROR: Could not obtain semaphore lock, Windows error code: 2
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} Program exited with code -536870910
[Thu Apr 12 16:36:37 2018 (G, 0)] {9303} ************************************************************
In particular, this article discusses details about possible causes for the "Windows error code: 2" detail shown after the message "Could not obtain semaphore lock".
Cause
The "Windows error code: 2" message is usually due to the system running out of semaphores to allocate.
Applications such as Oracle Database and Apache HTTP Server can use a lot of semaphores. Any application that consumes many semaphores without freeing them may lead to available semaphores being exhausted, with a symptom being the particular log message details described above.
Steps To Reproduce
- Reduce operating system semaphore limits to an unrealistically low number.
- Observe the error when running ndtrack,
Troubleshooting & Mitigation
Commands to investigate semaphore details will vary by operating system. Here are some examples of commands that can be used on Linux-based operating systems to troubleshoot this issue and find out if there are excessive semaphores in use by the system.
- Show current semaphore limits:
# ipcs -ls
------ Semaphore Limits --------
max number of arrays = 32000
max semaphores per array = 32000
max semaphores system wide = 1024000000
max ops per semop call = 500
semaphore max value = 32767
- Show current semaphore usage:
# ipcs -us
------ Semaphore Status --------
used arrays = 0
allocated semaphores = 0
- Show the processes associated with current semaphores in use:
# for pid in $(for semid in $(ipcs -s | awk '/0x/{ print $2 }'); do ipcs -s -i $semid | tail -2 | head -1 | awk '{print $5}'; done | sort -u); do ps uh -p $pid; done
After investigating the above you may notice that the semaphore limit is not set high enough or a process is using a lot of semaphores.
