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From "Bjoern Petri (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CELIX-233) Replace booleans as sync primitives
Date Fri, 15 May 2015 14:37:00 GMT
Bjoern Petri created CELIX-233:
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             Summary: Replace booleans as sync primitives
                 Key: CELIX-233
                 URL: https://issues.apache.org/jira/browse/CELIX-233
             Project: Celix
          Issue Type: Bug
            Reporter: Bjoern Petri
            Assignee: Bjoern Petri


In a lot of cases we use boolean variables (e.g. bool running) to determine whether a critical
section can be executed. Usually those variables are not declared volatile, so the they may
be cached in registers. Before the value in the register is written to memory, another thread
might be scheduled to run, resulting in that thread reading stale data.

But even when declaring a variable as volatile (although the volatile qualifier guarantees
that the reads and writes will happen in the exact order specified in the source code), the
compiler may generate code which reorders a volatile read or write with non-volatile reads
or writes, thus limiting its usefulness as an interthread flag or mutex.

That's why it should be preferable to use e.g. a mutex as sync primitive




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