fix issue that metric db_compaction_total_duration_milliseconds is always 0

[yingnanzhang666]

defer dbCompactionTotalMs.Observe(float64(time.Since(totalStart) / time.Millisecond))
Here, it will calculate float64(time.Since(totalStart) / time.Millisecond) when call defer directly and push into function stack, so the duration is quite small, less than 1 millisecond, so this value is always zero.

# HELP etcd_debugging_mvcc_db_compaction_total_duration_milliseconds Bucketed histogram of db compaction total duration.
# TYPE etcd_debugging_mvcc_db_compaction_total_duration_milliseconds histogram
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="100"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="200"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="400"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="800"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="1600"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="3200"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="6400"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="12800"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="25600"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="51200"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="102400"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="204800"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="409600"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="819200"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_bucket{le="+Inf"} 3564
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_sum 0
etcd_debugging_mvcc_db_compaction_total_duration_milliseconds_count 3564

[jingyih]

Thanks for the fix!

Can you change the title of the commit to <package>: <title>? In this case, it is something like mvcc: fix db_compaction_total_duration_milliseconds.

[yingnanzhang666]

@jingyih commit title is changed as your recommendation. thx.

[jingyih]

lgtm

[jingyih]

We should probably backport this. @jpbetz

[jpbetz]

Agreed. Here are the backports:

• 3.3 - Automated cherry pick of #10646 #10656
• 3.2 - Automated cherry pick of #10646 #10657
• 3.1 - Automated cherry pick of #10646 #10658