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Zheyuan Li
Asked: 2017-08-09 02:22:34 +0800 CST

sprof fails to generate flat profiling for my shared library: Inconsistency detected by ld.so

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I am unable to generate flat profiling result using sprof in Ubuntu 16.04.02 (as well as 14.04.01). Here is a reproducible example, adapted from man sprof.

First create a directory for experiment, then create prog.c and libdemo.c files inside:

// prog.c
       #include <stdlib.h>

       void x1(void);
       void x2(void);

       int
       main(int argc, char *argv[])
       {
           x1();
           x2();
           exit(EXIT_SUCCESS);
       }

// libdemo.c
       #include <unistd.h>

       void
       consumeCpu1(int lim)
       {
           int j;

           for (j = 0; j < lim; j++)
            getppid();
       }

       void
       x1(void) {
           int j;

           for (j = 0; j < 100; j++)
            consumeCpu1(200000);
       }

       void
       consumeCpu2(int lim)
       {
           int j;

           for (j = 0; j < lim; j++)
            getppid();
       }

       void
       x2(void)
       {
           int j;

           for (j = 0; j < 1000; j++)
            consumeCpu2(10000);
       }

Now open a terminal, and change directory to the above created one, then run the following shell script:

cc -g -fPIC -shared -o libdemo.so libdemo.c
cc -g -o prog prog.c -L. -ldemo

export LD_PROFILE=libdemo.so
export LD_PROFILE_OUTPUT=$(pwd)    ## use current directory
rm -f libdemo.so.profile
LD_LIBRARY_PATH=. ./prog
sprof -p libdemo.so libdemo.so.profile

I get an error:

Inconsistency detected by ld.so: dl-open.c: 717: _dl_open: Assertion `_dl_debug_initialize (0, args.nsid)->r_state == RT_CONSISTENT' failed!

libdemo.so.profile has been generated without problem, but sprof fails to process it.

I found this Stack Overflow thread What is causing sprof to complain about “inconsistency detected by ld.so”?, but it does not offer a solution. I want to get sprof to work!

Is this problem dependent on Linux distributions? I saw a thread on 2016, where sprof is successful: sprof flat profile name column has ugly format.

Frankly speaking I don't know which is the best forum to post this question. It looks like a programming question that belongs to Stack Overflow, but the C program and profiling runs alright; it is just sprof that fails to process it in the final stage, which should be a Linux related issue. Then if this issue is independent on Linux distributions, I should ask about on Unix & Linux, but if it only occurs on Ubuntu, I should raise it here on ask ubuntu. Well, feel free to migrate it to the best place as you see fit; I have no clue on it at all.

c

0 Answers