NEW 186726
SymbolTable wastes 3.5MB of HashTable capacity on cnn.com 
https://bugs.webkit.org/show_bug.cgi?id=186726
Summary SymbolTable wastes 3.5MB of HashTable capacity on cnn.com
Simon Fraser (smfr)
Reported 2018-06-16 12:19:41 PDT
Using tooling from bug 186698, loading can and running "notifyutil -p com.apple.WebKit.dumpHashTableCapacity" shows: Wasted capacity: 1570032 bytes (used 640016 of 2210048 bytes, utilization: 28.96%) - 6908 allocations 1 0x116698ef5 WTF::HashTable<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry> >, JSC::IdentifierRepHash, WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::KeyValuePairTraits, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > > >::HashTable() 2 0x116698ed5 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 3 0x11668fc05 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 4 0x11668fa6e JSC::SymbolTable::SymbolTable(JSC::VM&) 5 0x11668fc4d JSC::SymbolTable::SymbolTable(JSC::VM&) 6 0x11580d3a1 JSC::SymbolTable::create(JSC::VM&) 7 0x116690951 JSC::SymbolTable::cloneScopePart(JSC::VM&) 8 0x11575434c JSC::CodeBlock::setConstantRegisters(WTF::Vector<JSC::WriteBarrier<JSC::Unknown, WTF::DumbValueTraits<JSC::Unknown> >, 0ul, WTF::CrashOnOverflow, 16ul> const&, WTF::Vector<JSC::SourceCodeRepresentation, 0ul, WTF::CrashOnOverflow, 16ul> const&)
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Radar WebKit Bug Importer
Comment 1 2018-06-16 12:20:04 PDT
<rdar://problem/41189082>
Simon Fraser (smfr)
Comment 2 2018-06-16 12:21:08 PDT
As well as this one: Wasted capacity: 1291168 bytes (used 579168 of 1870336 bytes, utilization: 30.97%) - 5382 allocations 1 0x116698ef5 WTF::HashTable<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry> >, JSC::IdentifierRepHash, WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::KeyValuePairTraits, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > > >::HashTable() 2 0x116698ed5 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 3 0x11668fc05 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 4 0x11668fa6e JSC::SymbolTable::SymbolTable(JSC::VM&) 5 0x11668fc4d JSC::SymbolTable::SymbolTable(JSC::VM&) 6 0x11580d3a1 JSC::SymbolTable::create(JSC::VM&) 7 0x11580a7da JSC::BytecodeGenerator::BytecodeGenerator(JSC::VM&, JSC::FunctionNode*, JSC::UnlinkedFunctionCodeBlock*, JSC::DebuggerMode, JSC::VariableEnvironment const*) 8 0x1158116fd JSC::BytecodeGenerator::BytecodeGenerator(JSC::VM&, JSC::FunctionNode*, JSC::UnlinkedFunctionCodeBlock*, JSC::DebuggerMode, JSC::VariableEnvironment const*) and Wasted capacity: 713440 bytes (used 580896 of 1294336 bytes, utilization: 44.88%) - 147 allocations 1 0x116698ef5 WTF::HashTable<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry>, WTF::KeyValuePairKeyExtractor<WTF::KeyValuePair<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry> >, JSC::IdentifierRepHash, WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::KeyValuePairTraits, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > > >::HashTable() 2 0x116698ed5 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 3 0x11668fc05 WTF::HashMap<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> >, JSC::SymbolTableEntry, JSC::IdentifierRepHash, WTF::HashTraits<WTF::RefPtr<WTF::UniquedStringImpl, WTF::DumbPtrTraits<WTF::UniquedStringImpl> > >, JSC::SymbolTableIndexHashTraits>::HashMap() 4 0x11668fa6e JSC::SymbolTable::SymbolTable(JSC::VM&) 5 0x11668fc4d JSC::SymbolTable::SymbolTable(JSC::VM&) 6 0x11580d3a1 JSC::SymbolTable::create(JSC::VM&) 7 0x11657c560 JSC::JSSegmentedVariableObject::finishCreation(JSC::VM&) 8 0x1165084f3 JSC::JSGlobalObject::finishCreation(JSC::VM&, JSC::JSObject*)
Saam Barati
Comment 3 2018-06-17 11:36:24 PDT
Maybe we should consider a sorted vector here. I still think we should consider implementing Robin Hood hash tables
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