# Issue #59560: Memory leak risk in session pool usage in stats sync load

## Metadata
- Issue: https://github.com/pingcap/tidb/issues/59560
- Status: closed
- Type: type/bug
- Created At: 2025-02-15T11:19:17Z
- Closed At: 2025-02-18T13:48:28Z
- Labels: affects-7.5, affects-8.1, affects-8.5, impact/leak, report/customer, severity/major, sig/planner, type/bug

## Customer-Facing Phenomenon
- The exact reproduction steps are still unknown. But we observed memory leaks in production clusters:

## Linked PRs
- Related PR #59546: statistics: add Destroy method and handle session recycling
  URL: https://github.com/pingcap/tidb/pull/59546
  State: closed
  Merged At: 2025-02-18T13:48:26Z
  Changed Files Count: 21
  Main Modules: pkg/statistics, pkg/bindinfo, pkg/util, pkg/domain, pkg/ddl, pkg/planner/core
  Sample Changed Files:
  - pkg/bindinfo/global_handle.go
  - pkg/bindinfo/global_handle_test.go
  - pkg/bindinfo/tests/cross_db_binding_test.go
  - pkg/ddl/notifier/testkit_test.go
  - pkg/domain/domain.go
  - pkg/domain/infosync/info.go
  - pkg/planner/core/rule_collect_plan_stats.go
  - pkg/server/server.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle.go
  - pkg/statistics/handle/lockstats/lock_stats.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/syncload/stats_syncload.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/pool.go
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/testkit/mocksessionmanager.go
  - pkg/util/processinfo.go
  - pkg/util/session_pool.go
  PR Summary: What problem does this PR solve? Problem Summary: What changed and how does it work? ref This is an alternative API design to solve the problem. I believe explicitly using destroy instead of exposing implementation details is a better approach to fix it.
- Related PR #59614: statistics: add Destroy method and handle session recycling (#59546)
  URL: https://github.com/pingcap/tidb/pull/59614
  State: closed
  Merged At: 2025-02-21T10:39:54Z
  Changed Files Count: 24
  Main Modules: pkg/statistics, pkg/util, pkg/bindinfo, pkg/domain, DEPS.bzl, go.mod
  Sample Changed Files:
  - DEPS.bzl
  - go.mod
  - go.sum
  - pkg/bindinfo/global_handle.go
  - pkg/bindinfo/global_handle_test.go
  - pkg/ddl/notifier/testkit_test.go
  - pkg/domain/domain.go
  - pkg/domain/infosync/info.go
  - pkg/planner/core/rule_collect_plan_stats.go
  - pkg/server/server.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle.go
  - pkg/statistics/handle/lockstats/lock_stats.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/syncload/stats_syncload.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/pool.go
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/testkit/mocksessionmanager.go
  PR Summary: This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work? ref
- Related PR #59615: statistics: add Destroy method and handle session recycling (#59546)
  URL: https://github.com/pingcap/tidb/pull/59615
  State: closed
  Merged At: 2025-02-21T09:22:32Z
  Changed Files Count: 16
  Main Modules: pkg/statistics, pkg/domain, pkg/util, DEPS.bzl, go.mod, go.sum
  Sample Changed Files:
  - DEPS.bzl
  - go.mod
  - go.sum
  - pkg/domain/domain.go
  - pkg/domain/infosync/info.go
  - pkg/planner/core/plan_stats.go
  - pkg/server/server.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle_hist.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/testkit/mocksessionmanager.go
  - pkg/util/logutil/log.go
  - pkg/util/processinfo.go
  PR Summary: This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work? ref
- Related PR #59616: statistics: add Destroy method and handle session recycling (#59546)
  URL: https://github.com/pingcap/tidb/pull/59616
  State: open
  Merged At: not merged
  Changed Files Count: 21
  Main Modules: pkg/statistics, pkg/bindinfo, pkg/domain, pkg/util, DEPS.bzl, go.mod
  Sample Changed Files:
  - DEPS.bzl
  - go.mod
  - go.sum
  - pkg/bindinfo/global_handle.go
  - pkg/bindinfo/util.go
  - pkg/domain/domain.go
  - pkg/domain/infosync/info.go
  - pkg/planner/core/rule_collect_plan_stats.go
  - pkg/server/server.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle.go
  - pkg/statistics/handle/lockstats/lock_stats.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/syncload/stats_syncload.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/pool.go
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/testkit/mocksessionmanager.go
  - pkg/util/logutil/log.go
  PR Summary: This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work? ref
- Related PR #59634: statistics: add Destroy method and handle session recycling (#59546)
  URL: https://github.com/pingcap/tidb/pull/59634
  State: closed
  Merged At: 2025-02-19T06:52:10Z
  Changed Files Count: 12
  Main Modules: pkg/statistics, pkg/domain, pkg/planner/core, pkg/server, pkg/testkit, pkg/util
  Sample Changed Files:
  - pkg/domain/domain.go
  - pkg/domain/infosync/info.go
  - pkg/planner/core/plan_stats.go
  - pkg/server/server.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle_hist.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/testkit/mocksessionmanager.go
  - pkg/util/processinfo.go
  PR Summary: This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work? ref
- Related PR #59670: statistics: add Destroy method and handle session recycling (#59546) (#59634)
  URL: https://github.com/pingcap/tidb/pull/59670
  State: closed
  Merged At: not merged
  Changed Files Count: 12
  Main Modules: pkg/statistics, domain/domain.go, domain/infosync, pkg/planner/core, server/server.go, statistics/handle
  Sample Changed Files:
  - domain/domain.go
  - domain/infosync/info.go
  - pkg/planner/core/plan_stats.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - server/server.go
  - statistics/handle/handle_hist.go
  - testkit/mocksessionmanager.go
  - util/processinfo.go
  PR Summary: This is an automated cherry-pick of #59634 This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work?
- Related PR #59671: statistics: add Destroy method and handle session recycling (#59546)
  URL: https://github.com/pingcap/tidb/pull/59671
  State: closed
  Merged At: not merged
  Changed Files Count: 21
  Main Modules: pkg/statistics, pkg/bindinfo, domain/infosync, domain/session_pool_test.go, pkg/ddl, pkg/domain
  Sample Changed Files:
  - domain/infosync/info.go
  - domain/session_pool_test.go
  - pkg/bindinfo/global_handle.go
  - pkg/bindinfo/global_handle_test.go
  - pkg/bindinfo/tests/cross_db_binding_test.go
  - pkg/ddl/notifier/testkit_test.go
  - pkg/domain/domain.go
  - pkg/planner/core/rule_collect_plan_stats.go
  - pkg/statistics/handle/bootstrap.go
  - pkg/statistics/handle/handle.go
  - pkg/statistics/handle/lockstats/lock_stats.go
  - pkg/statistics/handle/storage/read.go
  - pkg/statistics/handle/syncload/stats_syncload.go
  - pkg/statistics/handle/util/BUILD.bazel
  - pkg/statistics/handle/util/pool.go
  - pkg/statistics/handle/util/util.go
  - pkg/statistics/handle/util/util_test.go
  - pkg/util/session_pool.go
  - server/server.go
  - testkit/mocksessionmanager.go
  PR Summary: This is an automated cherry-pick of #59546 What problem does this PR solve? Problem Summary: What changed and how does it work? ref

## Notes
- At least one merged PR was found. The merge timestamp above can be used as the fix landing time in the main branch.