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cmd/pprof: system addr2line isn't compatible #5039

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bradfitz opened this issue Mar 13, 2013 · 4 comments
Closed

cmd/pprof: system addr2line isn't compatible #5039

bradfitz opened this issue Mar 13, 2013 · 4 comments
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@bradfitz
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@bradfitz bradfitz commented Mar 13, 2013

"go tool pprof" seems to have regressed somehow.

bradfitz@bradfitzlap:~/go/test/bench/go1$ go test -c
....
bradfitz@bradfitzlap:~/go/test/bench/go1$ go tool pprof go1.test cpu.prof 
usage: addr2line binary
reads addresses from standard input and writes two lines for each:
    function name
    file:line
Welcome to pprof!  For help, type 'help'.
(pprof) top
Total: 187 samples
       9   4.8%   4.8%        9   4.8% 000000000052ce95
       6   3.2%   8.0%        6   3.2% 00000000004219eb
       5   2.7%  10.7%        5   2.7% 0000000000410b31
       3   1.6%  12.3%        3   1.6% 00000000004118a8
       2   1.1%  13.4%        2   1.1% 0000000000410211
       2   1.1%  14.4%        2   1.1% 00000000004119b9
       2   1.1%  15.5%        2   1.1% 000000000041e697
       2   1.1%  16.6%        2   1.1% 00000000004219e0
       2   1.1%  17.6%        2   1.1% 00000000004219e5
       2   1.1%  18.7%        2   1.1% 0000000000421c49
(pprof) 


$ which addr2line
/usr/bin/addr2line

$ addr2line --version
GNU addr2line (GNU Binutils for Ubuntu) 2.22

$ go tool addr2line 
usage: addr2line binary
reads addresses from standard input and writes two lines for each:
    function name
    file:line

If I modify misc/pprof:

diff -r f3ca7d5b1b0b misc/pprof
--- a/misc/pprof        Tue Mar 12 17:12:56 2013 -0700
+++ b/misc/pprof        Tue Mar 12 18:11:24 2013 -0700
@@ -4417,11 +4417,11 @@
     $cmd = "$addr2line --demangle -f -C -e $image";
   }
 
-  if (system("$addr2line --help >/dev/null 2>&1") != 0) {
+  #if (system("$addr2line --help >/dev/null 2>&1") != 0) {
     # addr2line must not exist.  Fall back to go tool addr2line.
     $addr2line = "go tool addr2line";
     $cmd = "$addr2line $image";
-  }
+ # }
 
   # If "addr2line" isn't installed on the system at all, just use
   # nm to get what info we can (function names, but not line numbers).

... then it works.

It seems we can't use the system addr2line anymore?

I don't know what the right fix is here but happy to send a CL if I'm told.
@remyoudompheng
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@remyoudompheng remyoudompheng commented Mar 13, 2013

Comment 1:

I don't think I have observed any regression. My addr2line is:
GNU addr2line (GNU Binutils) 2.23.1
on Archlinux and I never had problems. What happens if you echo/pipe the hex addresses
into "addr2line -f -C -e go1.test" ?
@rsc
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@rsc rsc commented Mar 13, 2013

Comment 2:

A change went in to pprof this morning to make it use go tool addr2line always, but I am
concerned that this is indicative of a deeper problem. I don't understand why
addr2line's help message got printed to the console when you ran pprof, and I don't
understand why the system addr2line doesn't work with Go binaries anymore. Both of those
need to be investigated and fixed before Go 1.1.
@gopherbot
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@gopherbot gopherbot commented Mar 13, 2013

Comment 3 by jeff.allen:

I found that it was pprof line 4653 that was choosing Go's addr2line over the system
addr2line.
https://code.google.com/p/go/source/browse/misc/pprof#4653
But then it was trying to use Go's addr2line with the system options and causing the
help message. The fix I proposed this morning was to never try to use system options,
since pprof is always finding addr2line instead.
@rsc
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@rsc rsc commented Mar 22, 2013

Comment 4:

Re #3, thank you very much for tracking that down. That's pretty subtle. I agree with
the fix now.

Status changed to WorkingAsIntended.

@rsc rsc added this to the Go1.1 milestone Apr 14, 2015
@rsc rsc removed the go1.1 label Apr 14, 2015
@golang golang locked and limited conversation to collaborators Jun 24, 2016
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