[SYSTEMDS-2073] Lost update on high frequency statistics maintenance

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: SystemML 1.1
• Assignee: Matthias Boehm
• Reporter: Matthias Boehm
• Created: 16/Jan/18 03:54
• Updated: 08/Mar/18 02:14
• Resolved: 16/Jan/18 22:36

Description

The recently introduced lock-free statistics maintenance (SYSTEMML-2069) has an issue of lost updates under high-frequency updates of hot opcodes. For example, the following script

parfor(j in 1:24)
   for(i in 1:10000000)
     q = nrow(Y);

 

gives the following statistics (counts of 240,000,000 are expected here)

 #  Instruction  Time(s)      Count
 1  nrow          95.118  239999993
 2  mvvar         64.423  239999957