[AMQ-8226] If ActiveMQ was started with low numer PID then activemq cli commands fails to check if ActiveMQ process is running.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.15.15, 5.16.2, 5.17.0
• Component/s: Command Line Tools
• Flags: Important
• Assignee: Jean-Baptiste Onofré
• Reporter: Roman Nieviezhyn
• Created: 15/Apr/21 19:02
• Updated: 10/Jan/22 10:29
• Resolved: 16/Apr/21 06:13

Description

State of the world

This commit introduced a new approach to check if the ActiveMQ process is running.

The new approach lists all processes with `ps` command and then greps it:
local RET="`ps -o "pid,args" | grep "^$activemq_pid\s.*java"`"

Issue

If ActiveMQ process was started with N digit PID and `ps` command returns processes with M digit PID (such that M > N) then `bin/activemq` script won't be able to identify if ActiveMQ is running. 

Example

$ ps -o "pid,args"
  PID COMMAND
   XX ActiveMQ java PROCESS
  XXX ANOTHER PROCESS 1
 XXXX ANOTHER PROCESS 2
XXXXX ANOTHER PROCESS N

In this example `ActiveMQ java PROCESS` is running with a two-digit PID `XX`.
`ANOTHER PROCESS N` is running with a five-digit PID `XXXXX`.

`ps` command will add additional spaces before the `ActiveMQ java PROCESS` to align it to the five-digit PID of `ANOTHER PROCESS N`.

In this case the grep experssion `^$activemq_pid\s.*java` wont be able to identify the `ActiveMQ java PROCESS` with PID `XX`.