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From "Hiroaki Yoshida (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-10186) FindBugs warnings: Random object created and used only once
Date Tue, 21 Aug 2018 01:29:00 GMT
Hiroaki Yoshida created FLINK-10186:
---------------------------------------

             Summary: FindBugs warnings: Random object created and used only once
                 Key: FLINK-10186
                 URL: https://issues.apache.org/jira/browse/FLINK-10186
             Project: Flink
          Issue Type: Bug
          Components: Streaming
            Reporter: Hiroaki Yoshida


FindBugs-3.0.1 ([http://findbugs.sourceforge.net/]) reported a DMI_RANDOM_USED_ONLY_ONCE warning
on master:
{code:java}
H B DMI: Random object created and used only once in new org.apache.flink.streaming.runtime.io.BufferSpiller(IOManager,
int)  At BufferSpiller.java:[line 118]
{code}
The description of the bug is as follows:
{quote}*DMI: Random object created and used only once (DMI_RANDOM_USED_ONLY_ONCE)*
This code creates a java.util.Random object, uses it to generate one random number, and then
discards the Random object. This produces mediocre quality random numbers and is inefficient.
If possible, rewrite the code so that the Random object is created once and saved, and each
time a new random number is required invoke a method on the existing Random object to obtain
it.

If it is important that the generated Random numbers not be guessable, you must not create
a new Random for each random number; the values are too easily guessable. You should strongly
consider using a java.security.SecureRandom instead (and avoid allocating a new SecureRandom
for each random number needed).
[http://findbugs.sourceforge.net/bugDescriptions.html#DMI_RANDOM_USED_ONLY_ONCE]
{quote}



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