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From: =?UTF-8?Q?Arne_Vajh=c3=b8j?= <arne@vajhoej.dk>
Newsgroups: comp.lang.java.programmer
Subject: Re: Starting jshell takes about 15 seconds
Date: Thu, 1 Aug 2019 21:03:50 -0400
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On 7/29/2019 4:01 AM, Andreas Leitgeb wrote:
> Arne Vajhøj <arne@vajhoej.dk> wrote:
>> On 7/28/2019 12:04 PM, Cecil Westerhof wrote:
>>> I have played with jshell before, but at the moment I am a bit more
>>> serious with it. Starting jshell between 15 and 20 seconds. Executing
>>> /reset takes 7 to 10 seconds.
>>> This seems a bit long to me. For example starting ipython3 takes less
>>> as two seconds. Is this normal, or is there a problem with my system?
>>> I am working with Debian 9.
>> Here starting jshell takes 1-3 seconds depending on the
>> system. Windows 7 and Ubuntu 18.04 both with Java 11.
> 
> The machine's RAM and # of cores may be more significant here
> than the OS or even the CPU or bogomips.
> 
> (And in case of enough RAM, then also whether jshell is already
> in the cache versus first-start.)
> 
> PS: Ubuntu here with 8GB on core i7 2.80GHz (HW about 10 years old):
>    first jshell start: roughly 6 secs, second one roughly 2 secs
> 
> $ time $JAVA12_HOME/bin/jshell <<< "/exit"
> |  Welcome to JShell -- Version 12.0.2
> |  For an introduction type: /help intro
> 
> jshell> |  Goodbye
> 
> real    0m1.708s      <--
> user    0m4.728s      <-- that's where # of cores comes in.
> sys     0m0.264s

Ah - it is multi-threaded.

My fast numbers were on 4c 12GB - the slow were on 1c 4GB.
Not first start.

Arne