[STORM-513] ShellBolt keeps sending heartbeats even when child process is hung

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.9.2-incubating
• Fix Version/s: 0.9.3-rc2
• Component/s: storm-multilang
• Environment: Linux: 2.6.32-431.11.2.el6.x86_64 (RHEL 6.5)
• Assignee: Jungtaek Lim
• Reporter: Dan Blanchard
• Created: 01/Oct/14 20:10
• Updated: 16/Nov/15 01:10
• Resolved: 14/Nov/14 21:54

Description

If I'm understanding everything correctly with how ShellBolts work, the Java ShellBolt executor is the part of the topology that sends heartbeats back to Nimbus to let it know that a particular multilang bolt is still alive. The problem with this is that if the multilang subprocess/bolt severely hangs (i.e., it will not even respond to SIGALRM and the like), the Java ShellBolt does not seem to notice or care. Simply having the tuple get replayed when it times out will not suffice either, because the subprocess will still be stuck.

The most obvious way to handle this seem to be to add heartbeating to the multilang protocol itself, so that the ShellBolt expects a message of some kind every timeout seconds.