gperftools

Given the following code that either calls f or g #include <stdlib.h> #include <stdio.h> int f() { return 0; } int g() { return 1; } int main() { long sum = 0; for(int i = 0; i < 1000*1000*1000; i++) { int result; if(rand() % 2 == 0) { result = f(); } else { result = g(); } sum += result; } printf("%ld\n", sum); } I compile with g++ test.c -o doom -lprofiler -lunwind And run with CPUPROFILE=./test.txt ./test And then generate a gif with pprof --gif ./test ./test.txt > output.gif I get the following However, I have edges going from f to g, and f to itself, and g to itself. There are no

gperftools documentation says that libprofiler should be linked into a target program: $ gcc myprogram.c -lprofiler (without changing a code of the program). And then program should be run with a specific environment variable: CPUPROFILE=/tmp/profiler_output ./a.out The question is: how does libprofile have a chance to start and finish a profiler when it is merely loaded, but its functions are not called? There is no constructor function in that library ( proof ). All occasions of "CPUPROFILE" in library code do not refer to any place where profiler is started. I am out of ideas, where to look