Seyreklik (veya yoğunluk), standart olmayan process.memoryUsage () ile NodeJS için ampirik olarak doğrulanabilir .
Bazen düğüm, diziyi seyrek tutacak kadar akıllıdır:
Welcome to Node.js v12.15.0.
Type ".help" for more information.
> console.log(`The script is using approximately ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024 * 100) / 100} MB`)
The script is using approximately 3.07 MB
undefined
> array = []
[]
> array[2**24] = 2**24
16777216
> array
[ <16777216 empty items>, 16777216 ]
> console.log(`The script is using approximately ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024 * 100) / 100} MB`)
The script is using approximately 2.8 MB
undefined
Bazen düğüm onu yoğunlaştırmayı seçer (bu davranış ileride optimize edilebilir):
> otherArray = Array(2**24)
[ <16777216 empty items> ]
> console.log(`The script is using approximately ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024 * 100) / 100} MB`)
The script is using approximately 130.57 MB
undefined
Sonra tekrar seyrek:
> yetAnotherArray = Array(2**32-1)
[ <4294967295 empty items> ]
> console.log(`The script is using approximately ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024 * 100) / 100} MB`)
The script is using approximately 130.68 MB
undefined
Bu nedenle, belki de orijinal AIX çekirdek hatası hakkında fikir edinmek için yoğun bir dizi kullanmak, benzer bir aralıkla zorlanmak zorunda kalabilir :
> denseArray = [...Array(2**24).keys()]
[
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,
48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95,
96, 97, 98, 99,
... 16777116 more items
]
> console.log(`The script is using approximately ${Math.round(process.memoryUsage().heapUsed / 1024 / 1024 * 100) / 100} MB`);
The script is using approximately 819.94 MB
undefined
Çünkü neden düşmesini sağlamıyorsun?
> tooDenseArray = [...Array(2**32-1).keys()]
<--- Last few GCs --->
[60109:0x1028ca000] 171407 ms: Scavenge 1072.7 (1090.0) -> 1056.7 (1090.0) MB, 0.2 / 0.0 ms (average mu = 0.968, current mu = 0.832) allocation failure
[60109:0x1028ca000] 171420 ms: Scavenge 1072.7 (1090.0) -> 1056.7 (1090.0) MB, 0.2 / 0.0 ms (average mu = 0.968, current mu = 0.832) allocation failure
[60109:0x1028ca000] 171434 ms: Scavenge 1072.7 (1090.0) -> 1056.7 (1090.0) MB, 0.2 / 0.0 ms (average mu = 0.968, current mu = 0.832) allocation failure
<--- JS stacktrace --->
==== JS stack trace =========================================
0: ExitFrame [pc: 0x100931399]
1: StubFrame [pc: 0x1008ee227]
2: StubFrame [pc: 0x100996051]
Security context: 0x1043830808a1 <JSObject>
3: [0x1043830b6919] [repl:1] [bytecode=0x1043830b6841 offset=28](this=0x104306fc2261 <JSGlobal Object>)
4: InternalFrame [pc: 0x1008aefdd]
5: EntryFrame [pc: 0x1008aedb8]
6: builtin exit frame: runInThisContext(this=0x104387b8cac1 <ContextifyScript map = 0x1043...
FATAL ERROR: invalid array length Allocation failed - JavaScript heap out of memory
Writing Node.js report to file: report.20200220.220620.60109.0.001.json
Node.js report completed
1: 0x10007f4b9 node::Abort() [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
2: 0x10007f63d node::OnFatalError(char const*, char const*) [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
3: 0x100176a27 v8::Utils::ReportOOMFailure(v8::internal::Isolate*, char const*, bool) [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
4: 0x1001769c3 v8::internal::V8::FatalProcessOutOfMemory(v8::internal::Isolate*, char const*, bool) [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
5: 0x1002fab75 v8::internal::Heap::FatalProcessOutOfMemory(char const*) [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
6: 0x1005f3e9b v8::internal::Runtime_FatalProcessOutOfMemoryInvalidArrayLength(int, unsigned long*, v8::internal::Isolate*) [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
7: 0x100931399 Builtins_CEntry_Return1_DontSaveFPRegs_ArgvOnStack_NoBuiltinExit [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
8: 0x1008ee227 Builtins_IterableToList [/Users/pzrq/.nvm/versions/node/v12.15.0/bin/node]
Abort trap: 6