Merge pull request #4036 from yandex/jemalloc-investigation

Added test script to reproduce performance degradation in jemalloc.

libs/libcommon/src/tests/CMakeLists.txt

@@ -7,6 +7,7 @@ add_executable (date_lut4 date_lut4.cpp)
 add_executable (date_lut_default_timezone date_lut_default_timezone.cpp)
 add_executable (multi_version multi_version.cpp)
 add_executable (local_date_time_comparison local_date_time_comparison.cpp)
+add_executable (realloc-perf allocator.cpp)
 
 set(PLATFORM_LIBS ${CMAKE_DL_LIBS})
 
@@ -17,6 +18,7 @@ target_link_libraries (date_lut4 common ${PLATFORM_LIBS})
 target_link_libraries (date_lut_default_timezone common ${PLATFORM_LIBS})
 target_link_libraries (multi_version common)
 target_link_libraries (local_date_time_comparison common)
+target_link_libraries (realloc-perf common)
 add_check(multi_version)
 add_check(local_date_time_comparison)
 

libs/libcommon/src/tests/allocator.cpp

@@ -0,0 +1,47 @@
+#include <cstdlib>
+#include <cstring>
+#include <vector>
+#include <thread>
+
+
+void thread_func()
+{
+    for (size_t i = 0; i < 100; ++i)
+    {
+        size_t size = 4096;
+
+        void * buf = malloc(size);
+        if (!buf)
+            abort();
+        memset(buf, 0, size);
+
+        while (size < 1048576)
+        {
+            size_t next_size = size * 4;
+
+            void * new_buf = realloc(buf, next_size);
+            if (!new_buf)
+                abort();
+            buf = new_buf;
+
+            memset(reinterpret_cast<char*>(buf) + size, 0, next_size - size);
+            size = next_size;
+        }
+
+        free(buf);
+    }
+}
+
+
+int main(int, char **)
+{
+    std::vector<std::thread> threads(16);
+    for (size_t i = 0; i < 1000; ++i)
+    {
+        for (auto & thread : threads)
+            thread = std::thread(thread_func);
+        for (auto & thread : threads)
+            thread.join();
+    }
+    return 0;
+}