sorter: fix unified sorter magic numbers & reduce memory consumption by channels (#1915)

[ti-chi-bot]

This is an automated cherry-pick of #1915

What problem does this PR solve?

• Unexpectedly large memory consumption by Unified Sorter when tables are many.
• Too many magic numbers in Unified Sorter.

What is changed and how it works?

• Reduce heapSorter inputCh size
• Add constants for some magic numbers used for sizes to better manage these sizes.

Check List

Tests

• Unit test
• Integration test

Related changes

• Need to cherry-pick to the release branch

Release note

• Fix Unified Sorter memory consumption when tables are many.

[liuzix]

/run-all-tests

[liuzix]

/run-all-tests

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.0@8bab5db). Click here to learn what that means.
The diff coverage is n/a.

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  Files                  ?        164           
  Lines                  ?      17540           
  Branches               ?          0           
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  Hits                   ?       9483           
  Misses                 ?       7062           
  Partials               ?        995           

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei
• overvenus

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[liuzix]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 9b14b0b

[amyangfei]

/merge

[amyangfei]

[2021-06-22T06:55:59.379Z] ----------------------------------------------------------------------

[2021-06-22T06:55:59.379Z] FAIL: config_test.go:81: serverConfigSuite.TestMarshal

[2021-06-22T06:55:59.379Z] 

[2021-06-22T06:55:59.379Z] config_test.go:89:

[2021-06-22T06:55:59.379Z]     c.Assert(b, check.Equals, `{"addr":"192.155.22.33:8887","advertise-addr":"","log-file":"","log-level":"info","gc-ttl":86400,"tz":"System","capture-session-ttl":10,"owner-flush-interval":200000000,"processor-flush-interval":100000000,"sorter":{"num-concurrent-worker":4,"chunk-size-limit":999,"max-memory-percentage":80,"max-memory-consumption":8589934592,"num-workerpool-goroutine":16,"sort-dir":"/tmp/cdc_sort"},"security":{"ca-path":"","cert-path":"","key-path":"","cert-allowed-cn":null},"per-table-memory-quota":20971520,"kv-client":{"worker-concurrent":8,"worker-pool-size":0}}`)

[2021-06-22T06:55:59.379Z] ... obtained string = "{\"addr\":\"192.155.22.33:8887\",\"advertise-addr\":\"\",\"log-file\":\"\",\"log-level\":\"info\",\"gc-ttl\":86400,\"tz\":\"System\",\"capture-session-ttl\":10,\"owner-flush-interval\":200000000,\"processor-flush-interval\":100000000,\"sorter\":{\"num-concurrent-worker\":4,\"chunk-size-limit\":999,\"max-memory-percentage\":30,\"max-memory-consumption\":17179869184,\"num-workerpool-goroutine\":16,\"sort-dir\":\"/tmp/cdc_sort\"},\"security\":{\"ca-path\":\"\",\"cert-path\":\"\",\"key-path\":\"\",\"cert-allowed-cn\":null},\"per-table-memory-quota\":20971520,\"kv-client\":{\"worker-concurrent\":8,\"worker-pool-size\":0}}"

[2021-06-22T06:55:59.380Z] ... expected string = "{\"addr\":\"192.155.22.33:8887\",\"advertise-addr\":\"\",\"log-file\":\"\",\"log-level\":\"info\",\"gc-ttl\":86400,\"tz\":\"System\",\"capture-session-ttl\":10,\"owner-flush-interval\":200000000,\"processor-flush-interval\":100000000,\"sorter\":{\"num-concurrent-worker\":4,\"chunk-size-limit\":999,\"max-memory-percentage\":80,\"max-memory-consumption\":8589934592,\"num-workerpool-goroutine\":16,\"sort-dir\":\"/tmp/cdc_sort\"},\"security\":{\"ca-path\":\"\",\"cert-path\":\"\",\"key-path\":\"\",\"cert-allowed-cn\":null},\"per-table-memory-quota\":20971520,\"kv-client\":{\"worker-concurrent\":8,\"worker-pool-size\":0}}"

[2021-06-22T06:55:59.380Z] 

[2021-06-22T06:55:59.380Z] OOPS: 5 passed, 1 FAILED

[2021-06-22T06:55:59.380Z] --- FAIL: Test (0.01s)

[2021-06-22T06:55:59.380Z] FAIL

[2021-06-22T06:55:59.380Z] coverage: 64.5% of statements

[2021-06-22T06:55:59.380Z] FAIL	github.com/pingcap/ticdc/pkg/config	0.047s

PTAL @liuzix

[amyangfei]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 85c4df4