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Posted to notifications@skywalking.apache.org by GitBox <gi...@apache.org> on 2021/04/12 04:27:08 UTC

[GitHub] [skywalking] nickwongwong commented on a change in pull request #6729: GlobalIdGenerator will produce a negative id when the time shift back

nickwongwong commented on a change in pull request #6729:
URL: https://github.com/apache/skywalking/pull/6729#discussion_r611319453



##########
File path: apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/context/ids/GlobalIdGenerator.java
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@@ -73,9 +73,19 @@ private long timestamp() {
             long currentTimeMillis = System.currentTimeMillis();
 
             if (currentTimeMillis < lastTimestamp) {
+                long overTime = lastTimestamp - currentTimeMillis;
+                if (overTime <= 5) {
+                    try {
+                        Thread.sleep(overTime);

Review comment:
       ![image](https://user-images.githubusercontent.com/16626084/114339294-6908b280-9b87-11eb-98f0-d95c44c2e2f1.png)
   Change `overTime` to 1ms.
   Use `LockSupport.parkNanos` instead of `Thread.sleep`.
   ![image](https://user-images.githubusercontent.com/16626084/114339407-b08f3e80-9b87-11eb-9fef-1b6968ca9de8.png)
   
   Actually, the `NTP` time offset(time shift) is very small in Linux servers.
   `1ms` may cover most cases, while keeping good performance.
   ![image](https://user-images.githubusercontent.com/16626084/114340192-96566000-9b89-11eb-96cf-246cb04d1a46.png)
   
   If ok, I will modify this PR.




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