RE: Memory Free up Failing on Solaris 8 - Off-topic

Hi

brk, sbrk functions are used for DATA segments and we have problem with HEAP. Malloc allocates space onto heap and not in DATA segment.

Seemingly the man page imply that it should not be used in conjunction with malloc, calloc , that we are using.

Pasting from man pages :-
"USAGE

     The behavior of brk() and sbrk() is unspecified if an appli-
     cation  also  uses  any  other  memory  functions  (such  as
     malloc(3C), mmap(2), free(3C))."

Qs. Is any alternative function which can be used OR am i missing something ?

Thanks

-----Original Message-----
Sent: Monday, February 03, 2003 1:19 PM
To: Multiple recipients of list ORACLE-L

hmm,

free() doesn't do sbrk() with a negative to reduce the process space. So yes the space stays allocated.

Anjo.

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Monday, February 03, 2003 7:58 AM

> Hi
>
> SITUATION - On a production APP Server having about 4000 Concurrent
application processes ,
> the memory allocated does NOT seem to be getting freed even though the
application program is issuing the respective call to Free the memory .
>
> Qs Any /etc/system parameters , OS patches which should help ?
>
> Qs Is our approach of using the pmap command Correct ?
> else what Command to find the "Private" memory taken up by a process would
be advisable ?
>
> Qs How to find the Total Amount of Swap Consumed ?
> [ We probably do NOT know how to interpret the vmstat output Correctly ,
> top/swap -s commands show an output Differing greatly from df -k output
for /tmp filesystem ]
>
> Qs Any Body has encountered such as situation before ?
>
>
> Configuration -
> Solaris 2.8
> Patch - Generic 108528-16 patch
> Machine SF15K
> CPUs = 36
> RAM = 96 GB
>
>
> We created a Small Sample C program which allocates & FREEs memory but
found that even after
> FREEing , the memory does NOT show as Freed in the pmap output . Is the
following approach correct ?
>
> DETAILS :-
>
> @@@@@@@@@@@@@@@@@ SAMPLE C PROGRAM @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
> #include <stdio.h>
> main()
> {
> char *abc = NULL ;
> int i = 0 ;
> for (i = 1; i < 10; i++){
> printf("allocating [%d] bytes\n", 10*1024*(i+1));
> abc = (char *)malloc(10*1024*(i+1));
> memset(abc, '\0', 10*1024*(i+1));
> getchar();
>
> free(abc);
> printf("Freeing [%d]\n", i);
> getchar();
> }
> exit() ;
> }
> @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
>
>
> RUN Output :-
>
> STEP 1 - allocating [20480] bytes
>
> pmap -x <PID of Above program process>
>
> Address Kbytes Resident Shared Private Permissions Mapped File
> 00010000 8 8 8 - read/exec a.out
> 00020000 8 8 - 8 read/write/exec a.out
> 00022000 24 24 - 24 read/write/exec [ heap ]
> FF280000 688 688 688 - read/exec libc.so.1
> FF33C000 32 32 - 32 read/write/exec libc.so.1
> FF370000 16 16 16 - read/exec libc_psr.so.1
> FF390000 8 8 8 - read/exec libdl.so.1
> FF3A0000 8 8 - 8 read/write/exec [ anon ]
> FF3B0000 152 152 152 - read/exec ld.so.1
> FF3E6000 8 8 - 8 read/write/exec ld.so.1
> FFBEC000 16 16 - 16 read/write/exec [ stack ]
> -------- ------ ------ ------ ------
> total Kb 968 968 872 96
>
> THE "Private" memory allocated by the [ heap ] is 24 K
>
> STEP 2 - Freeing the memory allocated in the above Step
>
> Freeing [1]
>
> pmap -x <PID of Above program process>
>
> Address Kbytes Resident Shared Private Permissions Mapped File
> 00022000 24 24 - 24 read/write/exec [ heap ]
>
> RESULT - THE "Private" memory allocated previously does NOT get Freed &
> [ heap ] continues to be 24 K
>
> STEP 3 -
> allocating [30720] bytes
>
> pmap -x <PID of Above Program process>
>
> Address Kbytes Resident Shared Private Permissions Mapped File
> 00022000 32 32 - 32 read/write/exec [ heap ]
>
> STEP 4 - Freeing the memory allocated in the above Step
> Freeing [2]
>
> pmap -x <PID of Above program process>
>
> Address Kbytes Resident Shared Private Permissions Mapped File
> 00022000 32 32 - 32 read/write/exec [ heap ]
>
> RESULT - THE "Private" memory allocated previously in Step 3 does NOT get
Freed &
> [ heap ] continues to be 32 K
>
> Thanks
>

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