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Date: Thu, 14 Apr 2016 16:33:56 -0400
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 <CAGzHvL=2a==vAAbz=+O1ubCVHKyh_-whn2djz_9qLy4=9u1FMA@mail.gmail.com>
Subject: parfor fails
From: Ethan Xu <ethan.yifanxu@gmail.com>
To: dev@systemml.incubator.apache.org
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Hello,

I have a quick question. The following script fails with this error:

org.apache.sysml.runtime.DMLRuntimeException: PARFOR: Failed to execute
loop in parallel.

Here is the dml script:

x=read($X);

print("number of rows of x = " + nrow(x));
print("number of cols of x = " + ncol(x));

parfor(i in 1:ncol(x), check=0){
    a = x[,i];
    print("number of 0's in col " + i + " = " + sum(a == 0));
}

where X is a 35 million by 2396 matrix (coded and dummy coded numerical
matrix) on HDFS. The script runs fine with regular 'for' loops.

Could someone explain why this script cannot run in parallel? Was it a
wrong way to code parfor?

Thanks,

Ethan

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