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https://issues.apache.org/jira/browse/HDDS-12459?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17932391#comment-17932391
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Tsz-wo Sze edited comment on HDDS-12459 at 3/4/25 5:43 PM:
-----------------------------------------------------------
{code:java}
public static void main(String[] args) throws Exception {
final Clock c = Clock.systemUTC();
final long startNano = System.nanoTime();
final Instant startInstant = c.instant();
for(int i = 0; i < 1000; i++) {
Thread.sleep(1000);
final long diffNano = System.nanoTime() - startNano;
final long diffInstantMs = c.instant().toEpochMilli() -
startInstant.toEpochMilli(); System.out.printf("%3d) %9.3f %9.3f%n", i,
diffNano/1000_000_000.0, diffInstantMs/1000.0);
}
{code}
The program above could show the problem if we change the system time when it
is running. A sample output is shown below:
{code:java}
13) 14.055 14.055
14) 15.058 15.058
15) 16.060 16.060
16) 17.063 17.063
17) 18.066 -3586.093
18) 19.071 -3585.087
19) 20.075 -3584.084
{code}
was (Author: szetszwo):
{code:java}
public static void main(String[] args) throws Exception {
final Clock c = Clock.systemUTC();
final long startNano = System.nanoTime();
final Instant startInstant = c.instant();
for(int i = 0; i < 1000; i++) {
Thread.sleep(1000);
final long diffNano = System.nanoTime() - startNano;
final long diffInstantMs = c.instant().toEpochMilli() -
startInstant.toEpochMilli(); System.out.printf("%3d) %9.3f %9.3f%n", i,
diffNano/1000_000_000.0, diffInstantMs/1000.0);
}
{code}
The program above could show the problem if we can the system time when it is
running. A sample output is shown below:
{code}
13) 14.055 14.055
14) 15.058 15.058
15) 16.060 16.060
16) 17.063 17.063
17) 18.066 -3586.093
18) 19.071 -3585.087
19) 20.075 -3584.084
{code}
> System clock should not be used for measuring time duration
> -----------------------------------------------------------
>
> Key: HDDS-12459
> URL: https://issues.apache.org/jira/browse/HDDS-12459
> Project: Apache Ozone
> Issue Type: Bug
> Reporter: Tsz-wo Sze
> Priority: Major
>
> java.time.Clock (system(ZoneId) / systemDefaultZone() / systemUTC()) uses
> System.currentTimeMillis(). As described in HADOOP-15901, this could result
> in undesired results when system clock's time changes.
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