asmhatreandClaude Sonnet 5.5
f80e1079a8
Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b7rnC7jppGGdHGESvy
17 lines
1016 B
Plaintext
17 lines
1016 B
Plaintext
ConcurrentHashMap.sizeCtl vs HashMap.threshold, single-threaded, read by reflection
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===================================================================================
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new ConcurrentHashMap() sizeCtl=0 table=null
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after 1st put sizeCtl=12 table.length=16
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after 12 puts (size=12) sizeCtl=24 table.length=32
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baseCount=12 counterCells=null size()=12 mappingCount()=12 (single thread: no CounterCell was ever needed)
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Sizing constructors: ask for 32 and see what each map really allocates
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new ConcurrentHashMap(32) sizeCtl=64 (table not allocated yet)
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after 1st put sizeCtl=48 table.length=64
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new HashMap(32) threshold=32 table=null (threshold holds the initial capacity until first put)
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after 1st put threshold=24 table.length=32
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What sizeCtl holds while a resize is running (computed, not caught live):
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resizeStamp(16)=32795 (rs << 16) + 2 = -2145714174 -> negative, so every other thread sees 'resize in progress'
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