Mutexes And Changes in Library Cache - HrOUG
Mutexes And Changes in Library Cache - HrOUG
Mutexes And Changes in Library Cache - HrOUG
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Purpose of <strong>Mutexes</strong><br />
• Mutex - mutual exclusion algorithms are used <strong>in</strong> so called<br />
critical section of the computer code to avoid the concurrent<br />
use of un-shareable resources.<br />
• Mutex is used with<strong>in</strong> Oracle as a low-level serialization<br />
mechanism to control access to shared data structures <strong>in</strong> the<br />
SGA. (Similarly like latches)<br />
• Serialization is required to avoid an object be<strong>in</strong>g:<br />
– read while someone is modify<strong>in</strong>g it<br />
– modified while someone is modify<strong>in</strong>g it<br />
– modified while someone is read<strong>in</strong>g it<br />
– de-allocated while someone is access<strong>in</strong>g it<br />
• S<strong>in</strong>ce Oracle 10gR2 mutexes are used to protect the shared<br />
cursor component of the library cache.<br />
www.dbprof.com - © 2012 Jože Senegačnik<br />
Oracle ACE Director<br />
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