[MAPREDUCE-6588] default values for PATH for tasks are not quite correct on Windows

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.6.0
• Component/s: mr-am
• Assignee: Unassigned
• Reporter: Sangjin Lee
• Created: 24/Dec/15 01:08
• Updated: 06/Jan/16 00:19

Description

There are several issues with the way PATH are handled for MR tasks and AMs on Windows.

• it does not get the PWD as part of the path, unlike the non-Windows case (see MAPREDUCE-6021)
• the MR AM doesn't get the Hadoop's bin directory in the path explicitly through mapred configuration; rather, it implicitly inherits it from the node manager (see MAPREDUCE-6577)
• the default value for the MR task PATH uses "%...%" macros which may be expanded on the client side prematurely; this is probably OK for tasks (as it's done by the AM), but not OK for AMs; the late-binding cross-platform macros should be used

I took a stab at addressing these as part of MAPREDUCE-6577, but I realized that it would be a bigger issue than the fix for MAPREDUCE-6577 itself. Thus, I'm filing a separate JIRA to address the Windows side of things.

On a related note, there are quite a few brittle tests on testing these (TestMiniMRChildTask, TestMiniMRClientCluster, etc.) which are built in such a way that the tests pass against the current behavior but don't provide a lot of robust test value. We should also update those tests to make them more robust.

Issue Links

• depends upon: MAPREDUCE-6577 MR AM unable to load native library without MR_AM_ADMIN_USER_ENV set
• is related to: MAPREDUCE-6021 MR AM should have working directory in LD_LIBRARY_PATH