Storages: limit memory usage of data sharing (#8567)

[ti-chi-bot]

This is an automated cherry-pick of #8567

What problem does this PR solve?

Issue Number: close #8564

Problem Summary:
In terms of design, we hope that by scheduling tasks, the shared data will be immediately read and deleted, so under normal circumstances, it will not occupy additional memory.
However, there is a scenario that would break this assumption: If two requests A and B are merged, request A reads faster and request B reads slowly.

A will share the data with B, but request B may skip directly without reading and deleting these shared data, because it finds its queue is full (

tiflash/dbms/src/Storages/DeltaMerge/ReadThread/MergedTask.cpp

Lines 81 to 84 in 11c0567

	if (pool->getFreeBlockSlots() <= 0 || pool->isRUExhausted())
	{
	continue;
	}

), which may result in consuming much more memory than expected.

What is changed and how it works?

This PR adds limitations on the size of shared data. It includes two aspects:

• Global shared data size limit.
• Limit on the count of shared data held by each DMFileReader.
  • Why not limit the size of shared data held by each DMFileReader?
  • First, it just holds a smart pointer. This pointer can be shared between multiple requests. How many bytes should it take? That needs some considerations.
  • Second, make changes smaller to pick this PR to other LST branches.
• Also, it supports disabling data sharing and doesn't affect read thead.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  • Run a fast tablescanning query and a slow tablescanning query concurrently.
  • In the image below,
    • on the left is the code of this PR, the limitation of shared data size is 1GB.
    • on the right is the code of master.

• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Fix a bug that the memory usage rises significantly when there are slow queries

[JinheLin]

/run-all-tests

[JinheLin]

/run-all-tests

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JinheLin, Lloyd-Pottiger

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Needs approval from an approver in each of these files:

• OWNERS [JinheLin,Lloyd-Pottiger]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-22 14:47:09.643632379 +0000 UTC m=+1231520.680859301: ☑️ agreed by JinheLin.
• 2023-12-24 13:08:12.206616901 +0000 UTC m=+1398383.243843827: ☑️ agreed by Lloyd-Pottiger.

[JaySon-Huang]

Changed to release note to be "Fix a bug that the memory usage rises significantly when there are slow queries"