[YARN-10019] container-executor: misc improvements in child processes and exec() calls

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.3.0
• Component/s: nodemanager
• Assignee: Peter Bacsko
• Reporter: Peter Bacsko
• Created: 07/Dec/19 15:47
• Updated: 11/Jan/20 00:18
• Resolved: 11/Jan/20 00:07

Description

There are a couple of improvements that we can do in container-executor regarding how we exit from child processes and how we handle failed exec() calls:

1. If we're in the child code path and we detect an erroneous condition, the usual way is just simply call _exit(). Normal exit() occurs in the parent. Calling _exit() prevents flushing stdio buffers twice and any cleanup logic registered with atexit() or on_exit() will run only once.

2. There's code like if (execlp(script_file_dest, script_file_dest, NULL) != 0) ... which is not necessary. Exec functions are not supposed to return. If they do, it's definitely an error, so no need to check the return value.