[DocDB] LeakSanitizer in MasterChangeConfigTest.TestChangeAllMasters

[bmatican]

Jira Link: DB-3429

Description

Seems like a test only issue

https://detective-gcp.dev.yugabyte.com/stability/test?branch=master&build_type=all&class=MasterChangeConfigTest&fail_tag=memory_leak&name=TestChangeAllMasters&platform=linux

https://jenkins.dev.yugabyte.com/job/github-yugabyte-db-alma8-master-clang12-asan/1232/artifact/build/asan-clang12-dynamic-ninja/yb-test-logs/tests-integration-tests__master_config-itest/MasterChangeConfigTest_TestChangeAllMasters.log

==201053==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 320 byte(s) in 1 object(s) allocated from:
    #0 0x7fe0182ccdfd in operator new(unsigned long) /opt/yb-build/llvm/yb-llvm-v12.0.1-yb-2-1659059070-22764466-almalinux8-x86_64-build/src/llvm-project/compiler-rt/lib/asan/asan_new_delete.cpp:99:3
    #1 0x7fe01719fd9e in yb::ExternalMiniCluster::StartShellMaster(yb::ExternalMaster**) ${BUILD_ROOT}/../../src/yb/integration-tests/external_mini_cluster.cc:510:28
    #2 0x239579 in yb::master::MasterChangeConfigTest_TestChangeAllMasters_Test::TestBody() ${BUILD_ROOT}/../../src/yb/integration-tests/master_config-itest.cc:389:15
    #3 0x7fdff46c21e2 in void testing::internal::HandleSehExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2402:10
    #4 0x7fdff46c21e2 in void testing::internal::HandleExceptionsInMethodIfSupported<testing::Test, void>(testing::Test*, void (testing::Test::*)(), char const*) /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2438:14
    #5 0x7fdff467e11f in testing::Test::Run() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2474:5
    #6 0x7fdff4680297 in testing::TestInfo::Run() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2656:11
    #7 0x7fdff46822df in testing::TestCase::Run() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2774:28
    #8 0x7fdff4698777 in testing::internal::UnitTestImpl::RunAllTests() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:4649:43
    #9 0x7fdff46c7c81 in bool testing::internal::HandleSehExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2402:10
    #10 0x7fdff46c7c81 in bool testing::internal::HandleExceptionsInMethodIfSupported<testing::internal::UnitTestImpl, bool>(testing::internal::UnitTestImpl*, bool (testing::internal::UnitTestImpl::*)(), char const*) /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:2438:14
    #11 0x7fdff4696c98 in testing::UnitTest::Run() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/src/gmock-1.8.0/googletest/src/gtest.cc:4257:10
    #12 0x7fe018c4891d in RUN_ALL_TESTS() /opt/yb-build/thirdparty/yugabyte-db-thirdparty-v20220806014317-c2f02d2024-almalinux8-x86_64-clang12/installed/asan/include/gtest/gtest.h:2233:46
    #13 0x7fe018c47ebd in main ${BUILD_ROOT}/../../src/yb/util/test_main.cc:109:13
    #14 0x7fdfed30ecf2 in __libc_start_main (/lib64/libc.so.6+0x3acf2)

[lingamsandeep]

This is a test specific issue. StartShellMaster returns a raw pointer to ExternalMaster which is then passed to ChangeConfig. ChangeConfig wraps the raw pointer in a scoped_refptr and so eventually it gets cleaned up properly. This explains why the test does not fail often. There is a leak only in case the test fails between StartShellMaster and ChangeConfig calls where we leak the ExternalMaster