Download as PDF, PPTX
![Mind the gap
byte[][][] b = new byte[10][100][1000];](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-26-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-27-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];
1.032.344=
1.000.000+
8.080(r)+20.220(h)+4.044(a)](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-28-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];
4.832.024=
1.000.000+
808.000(r)+2.020.020(h)+1.004.004(a)
1.032.344=
1.000.000+
8.080(r)+20.220(h)+4.044(a)](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-29-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];
4.832.024=
1.000.000+
808.000(r)+2.020.020(h)+1.004.004(a)
1.032.344=
1.000.000+
8.080(r)+20.220(h)+4.044(a)
x100](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-30-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];
4.832.024=
1.000.000+
808.000(r)+2.020.020(h)+1.004.004(a)
1.032.344=
1.000.000+
8.080(r)+20.220(h)+4.044(a)
x100 x100](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-31-2048.jpg)
![Mind the gap
byte[][][] b = new byte[1000][100][10];
byte[][][] b = new byte[10][100][1000];
4.832.024=
1.000.000+
808.000(r)+2.020.020(h)+1.004.004(a)
1.032.344=
1.000.000+
8.080(r)+20.220(h)+4.044(a)
x100 x100 x250](https://image.slidesharecdn.com/javamemorypresentation-140401171811-phpapp02/75/Java-memory-presentation-32-2048.jpg)
Uploaded byYury Bubnov
Java memory presentation
The document discusses various aspects of Java memory usage and garbage collection. It describes the Java heap structure, including the young generation, old generation, and survivor spaces. It also discusses object header information, memory addressing, and the impact of architecture (32-bit vs 64-bit) and JVM vendor (Oracle vs IBM) on object sizes. The garbage collection process of marking, sweeping, and compacting is explained.
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Similar to Java memory presentation
Java memory presentation
- 1.
- 2. Object o =new Object();
- 3. Object o =new Object(); java.lang.OutOfMemoryError: Java heap space
- 4. Object o =new Object(); java.lang.OutOfMemoryError: Java heap space
- 5.
- 6.
- 7.
- 8. class Structure{ byteb; short i; Object o; }
- 9. 1 2 4/8 classStructure{ byte b; short i; Object o; }
- 10. class Structure{ byteb; short i; Object o; } markmarkmark klass 2 1 1 4
- 11. class Structure{ byteb; short i; Object o; } 2 8 markmarkmark klass 2 1 1 4
- 12. class Structure{ byteb; short i; Object o; } markmarkmark klassklassklass 2 1 5 888
- 13. class Structure{ byteb; short i; Object o; } markmarkmark klassklassklass 2 1 5 888 4 8
- 14.
- 15.
- 16.
- 17. Memory address ...01100100100111011001011000 32 bitpointer .... to 35 bit
- 18. Memory address ...01100100100111011001011000 32 bitpointer .... to 35 bit 2^35≈32GB (25-28GB Heap)
- 19. Memory address ...01100100100111011001011000 32 bitpointer .... to 35 bit 2^35≈32GB (25-28GB Heap) IBM J9: Java 6 SR1- not enabled by default Hotspot: since Java 6u14, by default since u23
- 20. class Structure{ byteb; short i; Object o; } markmarkmarkmark klass 1 2 1 4 444
- 21. class Structure{ byteb; short i; Object o; } 3 8 markmarkmarkmark klass 1 2 1 4 444
- 22. klassklass flagsflags monitormonitor 44 13 2 2 =24b klassklassklassklass flagsflags size*size* monitormonitormonitormonitor 8888 1 3 2 2 klass flagsflagsflags monitor 1 33 4 22 2 =40b =24b i386 x64 x64C IBM J9
- 23. What’s the objectsize? class Structure{ byte b; short i; Object o;}
- 24. What’s the objectsize? HS 32b 16b HS 64b before u14 32b HS 64b after u14 (u27) 24b J9 32b 24b J9 64b 40b J9 64b compressed 24b class Structure{ byte b; short i; Object o;}
- 25.
- 26. Mind the gap byte[][][]b = new byte[10][100][1000];
- 27. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000];
- 28. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000]; 1.032.344= 1.000.000+ 8.080(r)+20.220(h)+4.044(a)
- 29. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000]; 4.832.024= 1.000.000+ 808.000(r)+2.020.020(h)+1.004.004(a) 1.032.344= 1.000.000+ 8.080(r)+20.220(h)+4.044(a)
- 30. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000]; 4.832.024= 1.000.000+ 808.000(r)+2.020.020(h)+1.004.004(a) 1.032.344= 1.000.000+ 8.080(r)+20.220(h)+4.044(a) x100
- 31. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000]; 4.832.024= 1.000.000+ 808.000(r)+2.020.020(h)+1.004.004(a) 1.032.344= 1.000.000+ 8.080(r)+20.220(h)+4.044(a) x100 x100
- 32. Mind the gap byte[][][]b = new byte[1000][100][10]; byte[][][] b = new byte[10][100][1000]; 4.832.024= 1.000.000+ 808.000(r)+2.020.020(h)+1.004.004(a) 1.032.344= 1.000.000+ 8.080(r)+20.220(h)+4.044(a) x100 x100 x250
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- 36.
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- 38.
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- 47.
- 48. Heap (HS) X XXXX X
- 49.
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- 51.
- 52. Heap (HS) X XXXX X
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- 61.
- 62. Garbage Collection 1. Startsif allocation fails or System.gc()* called or condition met
- 63. Garbage Collection 1. Startsif allocation fails or System.gc()* called or condition met 2. Stop-of-the-world operation
- 64. Garbage Collection 1. Startsif allocation fails or System.gc()* called or condition met 2. Stop-of-the-world operation 3. Mark, Sweep and Compact*
- 65.
- 66.
- 67.
- 68.
- 69.
- 70. A B 0 00 C D E 0 0 0 0 0 0 0 0 0 0 Mark A B C DE
- 71. 1 A B 0 0 CD E 0 0 0 0 0 0 0 0 0 0 A Mark A B C DE
- 72. 1 A B 0 C DE 0 0 0 0 0 0 0 0 0 Mark A B C DE B C 1 1
- 73. 1 A B 0 C DE 0 0 0 0 0 0 0 0 Mark A B C DE CE 1 1 1
- 74. 1 A B 0 C DE 0 0 0 0 0 0 0 0 Mark A B C DE E 1 1 1
- 75. 1 A B 0 C DE 0 0 0 0 0 0 0 0 Mark A B C DE 1 1 1
- 76. 1 A B CD E 0 0 0 Mark A B C DE 1 1 11 1 1 1 1 1
- 77. 1 A B CD E 0 0 0 Mark A B C DE 1 1 11 1 1 1 1 1
- 78.
- 79. References 1. Strong -always marked 2. Soft - not marked if too old or need memory 3. Weak - not marked if no strong reference 4. Phantom - correct implementation of finalize() method
- 80.
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- 91.
- 92. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 93. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 94. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 95. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 96. Sweep ... 1 00 1 1 1 0 0 0 1 1 ... Serial
- 97. Sweep ... 1 00 1 1 1 0 0 0 1 1 ... ... 1 0 0 1 1 1 0 0 0 1 1 ... ... 1 0 0 1 1 1 0 0 0 1 1 ...
- 98. Sweep ... 1 00 1 1 1 0 0 0 1 1 ... ... 1 0 0 1 1 1 0 0 0 1 1 ... ... 1 0 0 1 1 1 0 0 0 1 1 ...
- 99. Sweep ... 1 00 1 1 1 0 0 0 1 1 ... Parallel ... 1 0 0 1 1 1 0 0 0 1 1 ... ... 1 0 0 1 1 1 0 0 0 1 1 ...
- 100. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 101. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 102. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 103. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 104. Sweep ... 1 00 1 1 1 0 0 0 1 1 ...
- 105. Sweep ... 1 00 1 1 1 0 0 0 1 1 ... Concurrent
- 106. 1 1 00 1 1 1 0 0 0 1 1 ... Compact 1 1 1 1 1 1 1 0 0 0 0 0 ...
- 107. Garbage Collection Serial ParallelConcurrent Which one to choose?
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- 140. Paging 1. Linux/Windows useVirtual memory and “paging” to reference physical 2. Pages mapped to physical only when referenced 3. OS manages pages
- 141. Real size ofJava Process?
- 142. Real size ofJava Process? 1. Architecture: 32 vs 64
- 143. Real size ofJava Process? 1. Architecture: 32 vs 64 2. JVM vendor: Oracle vs IBM
- 144. Real size ofJava Process? 1. Architecture: 32 vs 64 2. JVM vendor: Oracle vs IBM 3. JVM version incl. update
- 145. Real size ofJava Process? 1. Architecture: 32 vs 64 2. JVM vendor: Oracle vs IBM 3. JVM version incl. update 4. JVM settings
- 146. Real size ofJava Process? 1. Architecture: 32 vs 64 2. JVM vendor: Oracle vs IBM 3. JVM version incl. update 5. OS (above applies) 4. JVM settings
- 147. Real size ofJava Process? 1. Architecture: 32 vs 64 2. JVM vendor: Oracle vs IBM 3. JVM version incl. update 5. OS (above applies) + Run under real load for long time 4. JVM settings
- 148.