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Posted to issues@systemml.apache.org by "Matthias Boehm (JIRA)" <ji...@apache.org> on 2018/01/16 03:55:00 UTC

[jira] [Created] (SYSTEMML-2073) Lost update on high frequency statistics maintenance

Matthias Boehm created SYSTEMML-2073:
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             Summary: Lost update on high frequency statistics maintenance
                 Key: SYSTEMML-2073
                 URL: https://issues.apache.org/jira/browse/SYSTEMML-2073
             Project: SystemML
          Issue Type: Bug
            Reporter: Matthias Boehm


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

{code}

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

{code}

 

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

{code}

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

{code}

 



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