[SYSTEMDS-553] Improve parfor dependency analysis

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: ParFor
• Assignee: Unassigned
• Reporter: Jon Deron Eriksson
• Created: 07/Mar/16 07:34
• Updated: 07/Mar/16 07:34

Description

The parfor dependency analysis can occasionally result in false positives. For example, as shown in the language reference, the following results in a false positive:

ms = matrix(0, rows=2, cols=3*10)
parfor (v in 1:10) { # parallizable - false positive
    mv = matrix(v, rows=2, cols=3)
    ms[,(v-1)*3+1:v*3] = mv
}

This can be circumvented with "check=0". However, it should be possible to infer certain situations like this so that no false positive arises.