[IMPALA-5454] JVM metrics don't show up on /memz sometimes

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.9.0
• Fix Version/s: Impala 2.10.0
• Epic Color: ghx-label-1
• Assignee: Henry Robinson
• Reporter: Henry Robinson
• Created: 07/Jun/17 22:20
• Updated: 08/Jun/17 22:47
• Resolved: 08/Jun/17 22:47

Description

Due to a bug in mustache.cc, memz.tmpl template rendering fails if the buffer_pool JSON entry is not generated.

The bug is that nested template commands with the same key aren't correctly parsed:

{{?b}} {{#b}}  {{/b}} {{/b}}

If 'b' is not present, the parser tries to skip to the closing

{{/b}}

, but does not take into account nesting and matches the first closing

{{/b}}

, not the second. Parsing then fails.

This JIRA is to track the workaround - rewriting the templates not to use nesting. The upstream project can fix the underlying issue independently.