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How to avoid frequent GCs due to Nursery Parts Limit (Doc ID 1638645.1)

Last updated on OCTOBER 10, 2018

Applies to:

Oracle JRockit - Version R28.2.0 and later
Information in this document applies to any platform.

Goal

This behavior has changed starting from JRockit Release 28.2.5, Full GC would be triggered once the Nursery Parts reach 10,000 (default value). This has been done to avoid Fragmentation.

GC logs would like below,

[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716813] [YC#14466] GC reason: Allocation request failed.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716813] [YC#14466] 1523972.432: YC started.
[INFO ][alloc  ][Wed Aug 28 17:38:36 2013][1377682716814] [YC#14466] Pending requests at 'Before YC' - Total: 1, TLAs: 1 (approx 524288 bytes), objects: 0 (0 bytes). Max age: 0.
[INFO ][nursery][Wed Aug 28 17:38:36 2013][1377682716814] [YC#14466] Forcing early OC because nursery parts 15504  more than limit 10000
[INFO ][nursery][Wed Aug 28 17:38:36 2013][1377682716814] [YC#14466] Young collection 14466 started. This YC is running while the OC is in phase: not running.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716850] [YC#14466] SemiRef phase WeakJNIHandles run in single threaded mode.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716861] [YC#14466] SemiRef phase ClassConstraints run in single threaded mode.

[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [YC#14466] YC promoted 181968 objects (18149KB).
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [YC#14466] Page faults before YC: 201, page faults after YC: 201, pages in heap: 3932160.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [YC#14466] Nursery size after YC: 0KB. (Free: 0KB Parts: 0)
[INFO ][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [YC#14466] 1523972.432-1523972.503: YC 6826318KB->6846996KB (15728640KB), 0.070 s, sum of pauses 69.764 ms, longest pause 69.764 ms.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [OC#83] GC reason: Allocation request failed.
[DEBUG][memory ][Wed Aug 28 17:38:36 2013][1377682716884] [OC#83] 1523972.503: OC started.
[INFO ][alloc  ][Wed Aug 28 17:38:36 2013][1377682716884] [OC#83] Pending requests at 'Before OC' - Total: 4, TLAs: 4 (approx 2097152 bytes), objects: 0 (0 bytes). Max age: 0.
[INFO ][compact][Wed Aug 28 17:38:36 2013][1377682716885] [OC#83] Compaction reason: Normal.
[INFO ][compact][Wed Aug 28 17:38:36 2013][1377682716885] [OC#83] Compacting 64 of 4096 parts at index 3968. Compaction type is external. Exceptional: No.
##################### REMOVED CERTAIN LINES ###########################
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726475] [OC#83] Setting keepAreaMarkers[1] to 0x133fd87d0.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726475] [OC#83] Setting keepAreaMarkers[2] to 0x17e4de420.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726475] [OC#83] Next keeparea will start at 0x133fd87d0 and end at 0x17e4de420.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726475] [OC#83] Nursery size increased from 0KB to 917504KB. Nursery list consists of 9383 parts.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Average part size: 98KB. Contraharmonic mean (CHM): 400KB. CHM per part: 0KB. Normalized CHM: 0.000436.
[DEBUG][memory ][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Total sweep time: 216.430 ms.
[DEBUG][memory ][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Ending sweeping phase.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Nursery size remains at 917504KB. Nursery list consists of 9383 parts.
[INFO ][nursery][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Average part size: 98KB. Contraharmonic mean (CHM): 400KB. CHM per part: 0KB. Normalized CHM: 0.000436.
[INFO ][alloc  ][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Satisfied 0 object and 17 tla allocations. Pending requests went from 17 to 0.
[INFO ][compact][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Average compact time ratio (move phase/total time): 1.000000.
[INFO ][compact][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Compaction time, total: 198.421 ms (target 333.333 ms).
[INFO ][compact][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Compaction moved 74574 objects and left 16 objects. Total moved size 14585216B.
[INFO ][compact][Wed Aug 28 17:38:46 2013][1377682726476] [OC#83] Compaction added 251652760B of free memory in 14 parts.

 

 

Solution

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In this Document
Goal
Solution
References


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