Slide 1
Slide 1 text
Minor GC
1. Let us assume that there are already objects on the Eden space when we
start(Blocks 01 to 06 marked as used memory)
2. The application creates a new object(07)
3. JVM tries to get required memory from Eden space, but there is no free space
in Eden to accommodate our object and hence JVM triggers minor GC
Slide 2
Slide 2 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
S0 S1
01 02 03 04 05 06
07
(new object)
Orphan Used memory Free memory
Slide 3
Slide 3 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
S0 S1
01 02 03 04 05 06
07
(new object)
Orphan Used memory Free memory
Slide 4
Slide 4 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
To survivor space
Orphan Used memory Free memory
S1
01
02
03
04
05
06
07
(new object)
Slide 5
Slide 5 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
To survivor space
Orphan Used memory Free memory
S1
01 03 05
07
(new object)
Slide 6
Slide 6 text
Second Minor GC
1. Let us assume that some time have passed and there are more objects on
the Eden space now(Blocks 07 to 13 marked as used memory)
2. The application creates a new object(14)
3. JVM tries to get required memory from Eden space, but there is no free space
in Eden to accommodate our object and hence JVM triggers second minor
GC
Slide 7
Slide 7 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
S0
S1
01 08 09 10 11 13
14
(new object)
Orphan Used memory Free memory
07 12
01 03 05
Slide 8
Slide 8 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
From survivor space To survivor space
01 08 09 10 11 13
14
(new object)
Orphan Used memory Free memory
07 12
01 03 05
Slide 9
Slide 9 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
From survivor space To survivor space
08 09 11
14
(new object)
Orphan Used memory Free memory
07
12
01 03
05
10 13
Slide 10
Slide 10 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
From survivor space S1
14
(new object)
Orphan Used memory Free memory
07
01 03
10 13
S0
Slide 11
Slide 11 text
13 more Minor GC cycles later
1. This keeps on repeating for each minor GC and the survivors are shifted
between S0 and S1 and their age is incremented. Once the age reaches the
"max age threshold", 15 by default, the object is moved to the "Tenured
space"
Slide 12
Slide 12 text
Minor GC
Heap memory
Young generation
Old generation
(Tenured space)
EDEN
Survivor space
S0 S1
14
Orphan Used memory Free memory
25
03
10 13
01
28 29