cdc/sorter: make unified sorter cgroup aware (#3436)

[ti-chi-bot]

This is an automated cherry-pick of #3436

What problem does this PR solve?

It fixes an OOM issue where memory limited by cgroup is smaller
than physical memory.

Note this patch only recognizes container cgroup, it may still
OOM when the cgroup is set by systemd or manually.

Cc https://github.com/pingcap/ticdc/issues/1798

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. mysql -h TIDBIP -P 4000 -u root -E -e 'update mysql.tidb set VARIABLE_VALUE="2400h" where VARIABLE_NAME="tikv_gc_life_time";'
2. tiup bench tpcc --host TIDBIP --port 4000 prepare -T 10 --warehouses 100
3. tiup bench tpcc --host TIDBIP --port 4000 run -T 10 --warehouses 100
4. run cdc in 8G memory docker container.
5. ./cdc cli --pd="http://PDIP" changefeed create
   --sink-uri="mysql://xx:xx@MYSQLIP:3306/" -c "mysql37"
   --start-ts=$(( $(pd-ctl -u http://PDIP service-gc-safepoint | jq '.service_gc_safe_points[] | select(.service_id == "gc_worker") | .safe_point') + 1000 ))
   --no-confirm --sort-engine=unified

OOM log in demsg

[Fri Nov 12 17:23:50 2021] CPU: 6 PID: 2542 Comm: cdc Kdump: loaded Tainted: G               ------------ T 3.10.0-1127.13.1.el7.x86_64 #1
[Fri Nov 12 17:23:50 2021] Hardware name: Dell Inc. PowerEdge R630/02C2CP, BIOS 2.4.3 01/17/2017
[Fri Nov 12 17:23:50 2021] Call Trace:
[Fri Nov 12 17:23:50 2021]  [<ffffffffa197ffa5>] dump_stack+0x19/0x1b
[Fri Nov 12 17:23:50 2021]  [<ffffffffa197a8c3>] dump_header+0x90/0x229
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1327aa4>] ? __css_tryget+0x24/0x50
[Fri Nov 12 17:23:50 2021]  [<ffffffffa13c24ce>] oom_kill_process+0x25e/0x3f0
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1333a01>] ? cpuset_mems_allowed_intersects+0x21/0x30
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1440c06>] mem_cgroup_oom_synchronize+0x546/0x570
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1440080>] ? mem_cgroup_charge_common+0xc0/0xc0
[Fri Nov 12 17:23:50 2021]  [<ffffffffa13c2d74>] pagefault_out_of_memory+0x14/0x90
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1978dd3>] mm_fault_error+0x6a/0x157
[Fri Nov 12 17:23:50 2021]  [<ffffffffa198d8d1>] __do_page_fault+0x491/0x500
[Fri Nov 12 17:23:50 2021]  [<ffffffffa198d975>] do_page_fault+0x35/0x90
[Fri Nov 12 17:23:50 2021]  [<ffffffffa1989778>] page_fault+0x28/0x30
[Fri Nov 12 17:23:50 2021] Task in /docker/2b34db4f57b5dff0b20a52ecbbdf1113450a5d19d86a68243bdd7814d4b743a6 killed as a result of limit of /docker/2b34db4f57b5dff0b20a52ecbbdf1113450a5d19d86a68243bdd7814d4b743a6
[Fri Nov 12 17:23:50 2021] memory: usage 8388608kB, limit 8388608kB, failcnt 41731
[Fri Nov 12 17:23:50 2021] memory+swap: usage 8388608kB, limit 16777216kB, failcnt 0
[Fri Nov 12 17:23:50 2021] kmem: usage 9100kB, limit 9007199254740988kB, failcnt 0
[Fri Nov 12 17:23:50 2021] Memory cgroup stats for /docker/2b34db4f57b5dff0b20a52ecbbdf1113450a5d19d86a68243bdd7814d4b743a6: cache:688KB rss:8378820KB rss_huge:0KB mapped_file:28KB swap:0KB inactive_anon:0KB active_anon:8378772KB inactive_file:152KB active_file:32KB unevictable:0KB
[Fri Nov 12 17:23:50 2021] [ pid ]   uid  tgid total_vm      rss nr_ptes swapents oom_score_adj name
[Fri Nov 12 17:23:50 2021] [33150]     0 33150      409       34       5        0             0 sh
[Fri Nov 12 17:23:50 2021] [35361]     0 35361      409       48       5        0             0 sh
[Fri Nov 12 17:23:50 2021] [36043]     0 36043      365       48       4        0             0 less
[Fri Nov 12 17:23:50 2021] [ 2532]     0  2532  2297379  2100625    4178        0             0 cdc
[Fri Nov 12 17:23:50 2021] Memory cgroup out of memory: Kill process 2621 (cdc) score 1003 or sacrifice child
[Fri Nov 12 17:23:50 2021] Killed process 2532 (cdc), UID 0, total-vm:9189516kB, anon-rss:8375780kB, file-rss:26720kB, shmem-rss:0kB

Left: master
Right: this PR

Related changes

• Need to cherry-pick to the release branch

Release note

Fix OOM in container environments.

[ti-chi-bot]

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[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 9986578