Std :: cout causes memory leak
I have a very simple C ++ program.
#include <iostream>
int main()
{
std::cout << "HI" << std::endl;
return 0;
}
I will compile this on Mac using the command c++ --std=c++11 leak.cpp
.
When I debug this with valgrind --leak-check=full ./a.out
I get the following output:
==2187== HEAP SUMMARY:
==2187== in use at exit: 38,906 bytes in 429 blocks
==2187== total heap usage: 508 allocs, 79 frees, 45,074 bytes allocated
==2187==
==2187== LEAK SUMMARY:
==2187== definitely lost: 0 bytes in 0 blocks
==2187== indirectly lost: 0 bytes in 0 blocks
==2187== possibly lost: 0 bytes in 0 blocks
==2187== still reachable: 4,096 bytes in 1 blocks
==2187== suppressed: 34,810 bytes in 428 blocks
==2187== Reachable blocks (those to which a pointer was found) are not shown.
==2187== To see them, rerun with: --leak-check=full --show-leak-kinds=all
It turns out there are 4096 bytes that are "still available". If I remove the instruction cout
, then there are no more "still reachable" bytes.
Why is it that the output is not std::cout
causing a memory leak?
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This could be a false positive in a leak report. Valgrind can be so smart; your standard library implementation accepts certain freedoms that Valgrind has no special case for.
I'm more worried about figuring out why this tiny program is doing 508 allocations, for a total of 45,074 bytes.
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