[HADOOP-14713] Audit for durations that should be measured via Time.monotonicNow

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Labels: newbie
• Assignee: Chetna Chaudhari
• Reporter: Jason Darrell Lowe
• Created: 01/Aug/17 18:18
• Updated: 24/Sep/17 19:16

Description

Whenever we are measuring a time delta or duration in the same process, the timestamps probably should be using Time.monotonicNow rather than Time.now or System.currentTimeMillis. The latter two are directly reading the system clock which can move faster or slower than actual time if the system is undergoing a time adjustment (e.g.: adjtime or admin sets a new system time).

We should go through the code base and identify places where the code is using the system clock but really should be using monotonic time.

Issue Links

• is related to: HDFS-12526 FSDirectory should use Time.monotonicNow for durations
• is related to: MAPREDUCE-6964 BaileyBorweinPlouffe should use Time.monotonicNow for measuring durations
• is related to: MAPREDUCE-6965 QuasiMonteCarlo should use Time.monotonicNow for measuring durations
• is related to: MAPREDUCE-6966 DistSum should use Time.monotonicNow for measuring durations
• is related to: MAPREDUCE-6967 gridmix/SleepReducer should use Time.monotonicNow for measuring durations
• is related to: HDFS-12243 Trash emptier should use Time.monotonicNow()
• is related to: HDFS-12538 TestInstrumentationService should use Time.monotonicNow
• relates to: HADOOP-14669 GenericTestUtils.waitFor should use monotonic time

Sub-Tasks

• ProtobufRpcEngine should use Time.monotonicNow to measure durations: Reopened
• LoadGenerator should use Time.monotonicNow() to measure durations: Resolved
• MetricsSystemImpl should use Time.monotonicNow for measuring durations: Resolved
• WritableRpcEngine should use Time.monotonicNow: Resolved
• ReflectionUtils should use Time.monotonicNow to mesaure duration: Resolved