Issue #7159 has been reported by kris7t (Kristóf Marussy).

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Bug #7159: SIGSEGV when calling Random#rand after forking
https://bugs.ruby-lang.org/issues/7159

Author: kris7t (Kristóf Marussy)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 1.9.3p194


When Kernel#fork is called,
Ruby uninitializes the default random generator Random::DEFAULT
by setting the next field of the struct MT that provides its state to 0.

Kernel#rand correctly initializes this random generator by a seed
when it detects this.
However, Random#rand does not do this and therefore attempting to
call Random#rand in a newly forked child process results in a
segmentation fault, because a null pointer is being dereferenced.

This irb session illustrates the problem:
https://gist.github.com/3888930


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