RFR: 8261768: SelfDestructTimer should accept seconds

[David Holmes]

On Mon, 23 May 2022 16:39:29 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

> The Java VM supports a runtime flag called `SelfDestructTimer`, which if used, will automatically terminate the java process using the value, expressed in minutes.
> 
> This flag is very useful when, for example, working on VM startup performance, as it allows a sampling tool to capture the exact same time interval for clear comparison of before and after optimizations.
> 
> The only problem is that the minimum value of 1 minutes is a really long time for a computer and any data captured during that minute will have many samples to filter through.
> 
> This fix allows SelfDestructTimer to accept a fractional value of minutes, which in practical terms allows for values to be expressed as seconds, which allows more flexible control.
> 
> For example:
> 
> - `XX:SelfDestructTimer=0.0` means that the feature is **off** (default, unchanged)
> - `XX:SelfDestructTimer=0.25` means **15 seconds**
> - `XX:SelfDestructTimer=0.5` means **30 seconds**
> - `XX:SelfDestructTimer=1.0` means **1 minute**
> 
> The implementation keeps the old semantics, so that`XX: SelfDestructTimer=1` behavior, for example, is unchanged.

This is a very old flag that predates diagnostic flags. :) Changing it to diagnostic would not be unreasonable IMO but a separate RFE.

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PR: https://git.openjdk.java.net/jdk/pull/8849