Measure size of HashMap [gives a good rough estimate] [1009433]

< > BotCompany Repo | #1009433 // Measure size of HashMap [gives a good rough estimate]

JavaX source code [tags: use-pretranspiled] - run with: x30.jar

!7

static int n = 20000;

p {
  for (int tableSize = 0; tableSize < 100; tableSize += 10) {
    O[] data = arrayOfBlankObjects(tableSize);
    O[] array = new O[n];
    long mem1 = usedMemoryAfterGC();
    for i over array: {
      new HashMap hashMap;
      for (O x : data) hashMap.put(x, x);
      array[i] = hashMap;
    }
    long mem2 = usedMemoryAfterGC();
    double objSize = (mem2-mem1)/(double) l(array);
    int rounded = iround(objSize);
    long f = guessHashMapSize(tableSize);
    print("Hash table size=" + tableSize + ". Approximate object size: " + objSize + " => " + rounded + " bytes. Formula: " + f);
  }
}

Author comment

Began life as a copy of #1009423

Travelled to 14 computer(s): aoiabmzegqzx, bhatertpkbcr, cbybwowwnfue, cfunsshuasjs, gwrvuhgaqvyk, ishqpsrjomds, lpdgvwnxivlt, mqqgnosmbjvj, pyentgdyhuwx, pzhvpgtvlbxg, tslmcundralx, tvejysmllsmz, vouqrxazstgt, wtqryiryparv

Snippet ID:

#1009433

Snippet name:

Measure size of HashMap [gives a good rough estimate]

Eternal ID of this version:

#1009433/6

Text MD5:

390e276ef3a79a53ddcb4fe0ac3670ad

Transpilation MD5:

a11a7f920c75be42028f9f399c422bd6

Author:

stefan

Category:

javax

Type:

JavaX source code

Public (visible to everyone):

Yes

Archived (hidden from active list):

Created/modified:

2017-08-01 20:05:33

Source code size:

649 bytes / 21 lines

Pitched / IR pitched:

No / No

Views / Downloads:

497 / 621

Version history:

5 change(s)

Referenced in:

[show references]

1	!7
2
3	static int n = 20000;
4
5	p {
6	for (int tableSize = 0; tableSize < 100; tableSize += 10) {
7	O[] data = arrayOfBlankObjects(tableSize);
8	O[] array = new O[n];
9	long mem1 = usedMemoryAfterGC();
10	for i over array: {
11	new HashMap hashMap;
12	for (O x : data) hashMap.put(x, x);
13	array[i] = hashMap;
14	}
15	long mem2 = usedMemoryAfterGC();
16	double objSize = (mem2-mem1)/(double) l(array);
17	int rounded = iround(objSize);
18	long f = guessHashMapSize(tableSize);
19	print("Hash table size=" + tableSize + ". Approximate object size: " + objSize + " => " + rounded + " bytes. Formula: " + f);
20	}
21	}