Re: [Qusetions] About the implemention of function gf_backtrace_fillframes

[Pranith Kumar Karampuri <pkarampu@xxxxxxxxxx>]

This is the patch which introduced this change, seems like the author wanted it work under memory pressure. I didn't read it carefully though.

    glusterd: Add last successful glusterd lock backtrace
   
    Also, moved the backtrace fetching logic to a separate function.
    Modified the backtrace fetching logic able to work under memory pressure
    conditions.
   
    Change-Id: Ie38bea425a085770f41831314aeda95595177ece
    BUG: 1138503
    Signed-off-by: Krishnan Parthasarathi <kparthas@xxxxxxxxxx>
    Reviewed-on: http://review.gluster.org/8584
    Tested-by: Gluster Build System <jenkins@xxxxxxxxxxxxxxxxx>
    Reviewed-by: Jeff Darcy <jdarcy@xxxxxxxxxx>
    Reviewed-by: Atin Mukherjee <amukherj@xxxxxxxxxx>

On Tue, Jun 20, 2017 at 8:38 AM, C0reFast <topchenfu@xxxxxx> wrote:

When I trying to listing /tmp in a gluster server. I found that have some bt prefix files like:

[root@xxx# ll /tmp/

ls: cannot access /tmp/btm1RpMm: No such file or directory

total 116

-rw-------  1 root root   129 Jan 13 17:11 bt0tJH3c

-?????????? ? ?    ?        ?            ? btm1RpMm

-rw-------  1 root root   287 Jan 13 17:11 btyDGNO9

drwx------. 2 root root 16384 Oct 19 09:21 lost+found

 

so i checked the source code. found in libglusterfs/src/common-utils.c

in function gf_backtrace_fillframes:

1. call frames = backtrace (array, GF_BACKTRACE_FRAME_COUNT); to get backtrace.

2. save backtrace to a temp file.

3. read backtrace from temp file to btbuf.

so why need writing a temp file instead just doing this in memory?

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--

Pranith

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