Memory Diagnostics – PGA Part 1
Memory Diagnostics – PGA Part 1
Second and very short post related to Oracle memory structures.This time I will focus on PGA .
Oracle offers many diffrents tools ( views, tables, dumps etc.. ) to gather information about these structures.This time I will introduce hidden oradebug options.
Reading these files is not difficult. There are also heap analyzers out there on internet.
Since these dump files looks very familiar I will just focus on commands and syntax.
This is 3 line script to perform these dumps:
oradebug setmypid
oradebug unit_test_nolg &p
oradebug tracefile_name
First command will dump PGAs information for all processes:
SQL> @od
Statement processed.
Enter value for p: dump_pga_details
Statement processed.
===============================================
PGA memory detail for pid 2, OS pid 13741
===============================================
2072 bytes, 3 chunks: “miscellaneous ” PL/SQL
multiple heaps ds=(nil) dsprt=(nil)
42928 bytes, 90 chunks: “miscellaneous “
multiple heaps ds=(nil) dsprt=(nil)
155824 bytes, 20 chunks: “permanent memory “
pga heap ds=0x9e5fa20 dsprt=(nil)
53120 bytes, 2 chunks: “free memory “
session heap ds=0x2aaaabd66998 dsprt=0x9e65120
44608 bytes, 1 chunk : “permanent memory “
session heap ds=0x2aaaabd66998 dsprt=0x9e65120
32792 bytes, 1 chunk : “permanent memory “
———————————————————-
===============================================
PGA memory detail for pid 3, OS pid 13743
===============================================
141976 bytes, 18 chunks: “permanent memory “
pga heap ds=0x9e5fa20 dsprt=(nil)
53120 bytes, 2 chunks: “free memory “
session heap ds=0x2aaaabd66998 dsprt=0x9e65120
44608 bytes, 1 chunk : “permanent memory “
session heap ds=0x2aaaabd66998 dsprt=0x9e65120
32792 bytes, 1 chunk : “permanent memory “
top call heap ds=0x9e64f00 dsprt=(nil)
31608 bytes, 1 chunk : “free memory “
top call heap ds=0x9e64f00 dsprt=(nil)
31328 bytes, 1 chunk : “Fixed Uga “
pga heap ds=0x9e5fa20 dsprt=(nil)
27248 bytes, 6 chunks: “free memory
——————————————————————
Here is second command.Self explanatory.
SQL> oradebug unit_test_nolg dump_top_pga
Statement processed.
*** 2009-06-19 15:54:10.612
******************************************************
HEAP DUMP heap name=”pga heap” desc=0x9e5fa20
extent sz=0x20c0 alt=184 het=32767 rec=0 flg=2 opc=2
parent=(nil) owner=(nil) nex=(nil) xsz=0xfff0 heap=(nil)
fl2=0×60, nex=(nil)
EXTENT 0 addr=0x2aaaac090010
Chunk 2aaaac090020 sz= 34176 free ” “
Chunk 2aaaac0985a0 sz= 31328 freeable “Fixed Uga “
EXTENT 1 addr=0x2aaaac080010
Chunk 2aaaac080020 sz= 34768 perm “perm ” alo=8624
Chunk 2aaaac0887f0 sz= 19256 free ” “
Chunk 2aaaac08d328 sz= 4224 freeable “Alloc environm ” ds=0x2aaaabc97620
Chunk 2aaaac08e3a8 sz= 4224 freeable “Alloc environm ” ds=0x2aaaabc97620
Chunk 2aaaac08f428 sz= 592 freeable “kopolal void “
Chunk 2aaaac08f678 sz= 432 freeable “kopolal void “
Chunk 2aaaac08f828 sz= 344 freeable “kopolal void “
Chunk 2aaaac08f980 sz= 592 freeable “kopolal void “
Chunk 2aaaac08fbd0 sz= 1072 freeable “kopolal void “
EXTENT 2 addr=0x2aaaabcd1e70
Chunk 2aaaabcd1e80 sz= 4184 freeable “diag pga ” ds=0x2aaaabb547a0
Chunk 2aaaabcd2ed8 sz= 4184 freeable “diag pga ” ds=0x2aaaabb547a0
EXTENT 3 addr=0x2aaaabccfd80
Chunk 2aaaabccfd90 sz= 4184 freeable “diag pga ” ds=0x2aaaabb547a0
Chunk 2aaaabcd0de8 sz= 4184 freeable “diag pga ” ds=0x2aaaabb547a0
EXTENT 4 addr=0x2aaaabccdc80
Chunk 2aaaabccdc90 sz= 8384 freeable “diag pga ” ds=0x2aaaabb547a0
EXTENT 5 addr=0x2aaaabccbb80
We can accomplish this by running these commands with certain level
oradebug dump HEAPDUMP
oradebug dump PGA_DETAIL_GET
oradebug dump PGA_DETAIL_DUMP
oradebug dump PGA_DETAIL_CANCEL
etc..
Here is useful addition.Using this command I can perform heap stress with different number of iterations and various number of subheaps and buffers.
Heap stress test:
SQL> @od
Statement processed.
Enter value for p: heap_stress_test 100
Statement processed.
*** 2009-06-19 15:43:50.205
iterations: 100
maximum subheaps: 2
maximum buffers: 14
maximum bytes allocated: 450348
cumulative bytes allocated: 1636817
******************************************************
HEAP DUMP heap name=”pga heap” desc=0x9e5fa20
extent sz=0x20c0 alt=184 het=32767 rec=0 flg=2 opc=3
parent=(nil) owner=(nil) nex=(nil) xsz=0xfff0 heap=(nil)
fl2=0×60, nex=(nil)
EXTENT 0 addr=0x2aaaac9a5010
Chunk 2aaaac9a5020 sz= 1320 free ” “
Chunk 2aaaac9a5548 sz= 160 freeable “ksmhs subheap d”
Chunk 2aaaac9a55e8 sz= 64024 free ” “
EXTENT 1 addr=0x2aaaac995010
Chunk 2aaaac995020 sz= 12416 free ” “
Chunk 2aaaac9980a0 sz= 19512 freeable “ksmhs buffer “
Chunk 2aaaac99ccd8 sz= 33576 freeable “ksmhs buffer “
EXTENT 2 addr=0x2aaaac985010
Chunk 2aaaac985020 sz= 1136 free ” “
Chunk 2aaaac985490 sz= 3120 freeable “ksmhs buffer “
Chunk 2aaaac9860c0 sz= 8560 free ” “
Chunk 2aaaac988230 sz= 52688 freeable “ksmhs buffer “
EXTENT 3 addr=0x2aaaac975010
Chunk 2aaaac975020 sz= 9080 free ” “
Chunk 2aaaac977398 sz= 16704 freeable “ksmhs buffer “
Chunk 2aaaac97b4d8 sz= 39720 freeable “ksmhs subheap ” ds=0x2aaaac9a5560
EXTENT 4 addr=0x2aaaac0d0010
Chunk 2aaaac0d0020 sz= 21032 free ” “
Chunk 2aaaac0d5248 sz= 44472 freeable “ksmhs subheap ” ds=0x2aaaac9a5560
SQL> @od
Statement processed.
Enter value for p: heap_stress_test 1000
Statement processed.
*** 2009-06-19 15:44:02.223
iterations: 1000
maximum subheaps: 8
maximum buffers: 18
maximum bytes allocated: 560147
cumulative bytes allocated: 15866914
******************************************************
HEAP DUMP heap name=”pga heap” desc=0x9e5fa20
extent sz=0x20c0 alt=184 het=32767 rec=0 flg=2 opc=3
parent=(nil) owner=(nil) nex=(nil) xsz=0xfff0 heap=(nil)
fl2=0×60, nex=(nil)
EXTENT 0 addr=0x2aaaaca35010
Chunk 2aaaaca35020 sz= 21440 free ” “
Chunk 2aaaaca3a3e0 sz= 44064 freeable “ksmhs buffer “
EXTENT 1 addr=0x2aaaaca05010
Chunk 2aaaaca05020 sz= 5632 free ” “
Chunk 2aaaaca06620 sz= 160 freeable “ksmhs subheap d”
Chunk 2aaaaca066c0 sz= 112 freeable “ksmhs subheap i”
Chunk 2aaaaca06730 sz= 125136 free ” “
EXTENT 2 addr=0x2aaaac9a5010
Chunk 2aaaac9a5020 sz= 88 free ” “
Chunk 2aaaac9a5078 sz= 160 freeable “ksmhs subheap d”
Chunk 2aaaac9a5118 sz= 112 freeable “ksmhs subheap i”
Chunk 2aaaac9a5188 sz= 160 freeable “ksmhs subheap d”
Chunk 2aaaac9a5228 sz= 112 freeable “ksmhs subheap i”
Chunk 2aaaac9a5298 sz= 48016 free ” “
Chunk 2aaaac9b0e28 sz= 16856 recreate “ksmhs subheap ” latch=(nil)
ds 2aaaac9a5090 sz= 16856 ct= 1
SQL> @od
Statement processed.
Enter value for p: heap_stress_test 10000
Statement processed.
*** 2009-06-19 15:44:13.028
iterations: 10000
maximum subheaps: 14
maximum buffers: 43
maximum bytes allocated: 1548196
cumulative bytes allocated: 168945876
******************************************************
HEAP DUMP heap name=”pga heap” desc=0x9e5fa20
extent sz=0x20c0 alt=184 het=32767 rec=0 flg=2 opc=3
parent=(nil) owner=(nil) nex=(nil) xsz=0xfff0 heap=(nil)
fl2=0×60, nex=(nil)
EXTENT 0 addr=0x2aaaacae5010
Chunk 2aaaacae5020 sz= 46208 free ” “
Chunk 2aaaacaf04a0 sz= 19296 freeable “ksmhs buffer “
EXTENT 1 addr=0x2aaaac1b5010
Chunk 2aaaac1b5020 sz= 60872 free ” “
Chunk 2aaaac1c3de8 sz= 8000024 freeable “ksmhs buffer pt”
EXTENT 2 addr=0x2aaaac0e5010
Chunk 2aaaac0e5020 sz= 51912 free ” “
Chunk 2aaaac0f1ae8 sz= 800024 freeable “ksmhs subheap p”
EXTENT 3 addr=0x2aaaac090010
Chunk 2aaaac090020 sz= 34176 free ” “
Chunk 2aaaac0985a0 sz= 31328 freeable “Fixed Uga “
EXTENT 4 addr=0x2aaaac080010
Also I can use Oracle events to collect additional data about PGA but I will write about it when I get a chance.