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Garbage Collection
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(Continued from previous part...)
GCTest Program Output - Periodical Memory Requirement
In this test, I ran the same program un J2SDK 1.4.0_02 with a different parameter:
java -Xms2m -Xmx8m GCTest 16 8 > tail_16_08.out
I got the following output:
Time Total Free Free Total Act. Dead Over
sec. Mem. Mem. Per. Obj. Obj. Obj. Head
0 1984 1727 87% 0 0 0 257
0 1984 1593 80% 128 128 0 263
1 1984 1464 73% 256 256 0 264
1 1984 1334 67% 384 384 0 266
....
5 1984 425 21% 1280 1280 0 279
5 1984 296 14% 1408 1408 0 280
6 3124 1451 46% 1536 1408 128 137
6 3124 1450 46% 1536 1536 0 138
....
10 3124 412 13% 2560 2560 0 152
11 3124 282 9% 2688 2688 0 154
11 5256 2303 43% 2816 2816 0 137
12 5256 2173 41% 2944 2944 0 139
12 5256 2043 38% 3072 3072 0 141
....
27 5256 329 6% 4736 2688 2048 191
27 5256 199 3% 4864 2816 2048 193
28 8128 2998 36% 2944 2944 0 2186
28 8128 2868 35% 3072 3072 0 2188
29 8128 2866 35% 3072 2944 128 2190
29 8128 2864 35% 3072 2816 256 2192
30 8128 2863 35% 3072 2688 384 2193
30 8128 2861 35% 3072 2560 512 2195
....
47 8128 754 9% 5120 2304 2816 2254
48 8128 752 9% 5120 2176 2944 2256
48 8128 750 9% 5120 2048 3072 2258
49 8128 620 7% 5248 2176 3072 2260
49 8128 491 6% 5376 2304 3072 2261
50 8128 361 4% 5504 2432 3072 2263
50 8128 231 2% 5632 2560 3072 2265
51 8128 2230 27% 2688 2688 0 3210
51 8128 2100 25% 2816 2816 0 3212
52 8128 1970 24% 2944 2944 0 3214
52 8128 1840 22% 3072 3072 0 3216
53 8128 1839 22% 3072 2944 128 3217
53 8128 1837 22% 3072 2816 256 3219
54 8128 1835 22% 3072 2688 384 3221
54 8128 1833 22% 3072 2560 512 3223
....
66 8128 385 4% 4480 2432 2048 3263
66 8128 256 3% 4608 2560 2048 3264
67 8128 3254 40% 2688 2688 0 2186
67 8128 3124 38% 2816 2816 0 2188
68 8128 2995 36% 2944 2944 0 2189
68 8128 2865 35% 3072 3072 0 2191
69 8128 2863 35% 3072 2944 128 2193
69 8128 2861 35% 3072 2816 256 2195
70 8128 2860 35% 3072 2688 384 2196
70 8128 2858 35% 3072 2560 512 2198
....
90 8128 358 4% 5504 2432 3072 2266
90 8128 228 2% 5632 2560 3072 2268
91 8128 2230 27% 2688 2688 0 3210
91 8128 2100 25% 2816 2816 0 3212
92 8128 1970 24% 2944 2944 0 3214
92 8128 1840 22% 3072 3072 0 3216
93 8128 1839 22% 3072 2944 128 3217
93 8128 1837 22% 3072 2816 256 3219
94 8128 1835 22% 3072 2688 384 3221
94 8128 1833 22% 3072 2560 512 3223
....
This time, the program allocated 2048KB of objects during the initialization
phase. Then it started the test loop phase of allocating 1024KB of objects
before release the same amount of objects.
By looking at the output, the periodic change of memory requirement between
2048KB and 3072KB had no impact on the garbarge collection process.
Then I increased the memory requirement with:
java -Xms2m -Xmx8m GCTest 16 16 > tail_16_16.out
(Continued on next part...)
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