java.lang.Instant comes with Java 8 but there it does not have microsecond 
precision yet (it can store even nanoseconds but they are all zeros).

Personally I don't see much reason for microsecond precision in logs either, 
but perhaps it could be an option.

-Harri

-----Original Message-----
From: Mark Thomas <[email protected]> 
Sent: perjantai 12. syyskuuta 2025 17.44
To: Tomcat Users List <[email protected]>
Subject: Re: Support for microsecond precision in timestamps (Tomcat 9.0.108 / 
10.1.44)

On 12/09/2025 13:00, Poojashree Prakash wrote:
> +1
> Java9 and above supports precision logging -  timestamp - Current time 
> in microseconds in java - Stack Overflow 
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsta
> ckoverflow.com%2Fquestions%2F1712205%2Fcurrent-time-in-microseconds-in
> -java&data=05%7C02%7Charri.pesonen%40sinch.com%7C668025699f024c646b6f0
> 8ddf20af08e%7C3b518aae89214a7b8497619d756ce20e%7C0%7C0%7C6389328510157
> 79455%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAw
> MCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdat
> a=33veKYxAmaT4XVPSo65DLVb7T31t%2BZaujXAG6HHqNjk%3D&reserved=0>
> Also considering - Apache Tomcat(r) - Which Version Do I Want?
> <https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftom
> cat.apache.org%2Fwhichversion.html&data=05%7C02%7Charri.pesonen%40sinc
> h.com%7C668025699f024c646b6f08ddf20af08e%7C3b518aae89214a7b8497619d756
> ce20e%7C0%7C0%7C638932851015805837%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1
> hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUI
> joyfQ%3D%3D%7C0%7C%7C%7C&sdata=qSqG%2BLOpgY1iZSBhK2PmGaQ1lp0i2m2O6wGCU
> HBjIWM%3D&reserved=0>
> 
> tomcat11 Supports java 17 and above
> tomcat10 Support java 11 and above
> tomcat9 Supports java 8 and above
> So, does Tomcat provide any way to log access timestamps with 
> microsecond precision?
> If not, is there an upcoming plan to enable true microsecond precision 
> in timestamps for Tomcat logs?

I stand corrected.

There are no currently plans for microsecond precision in timestamps for either 
logs or the access log.

There are a number of things any implementation would need to take account of:

- Tomcat 9 has a minimum Java version of 8 so Instant might not be
   available for log messages. It is likely some form of JreCompat based
   solution would be required for Tomcat 9

- Converting the timestamps to strings would need some thought. The
   timestamp to String conversions in Tomcat are heavily optimised for
   performance. Work would be required to determine if that were still
   necessary and, if it were, to develop appropriate solutions

- The access log valve implementations would need to be converted to use
   Instant. A bigger issue is the API uses milliseconds. The API and
   configuration would need to be updated in a backwards compatible way
   for this to be available on anything earlier than Tomcat 12.

All of which begs the question. Why? What is it that you are trying to do that 
you can't do with the current millisecond logs and microseconds for request 
processing time?

Mark


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