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From: Cecil Westerhof <Cecil@decebal.nl>
Newsgroups: comp.lang.java.programmer
Subject: Re: Starting jshell takes about 15 seconds
Date: Mon, 29 Jul 2019 21:10:36 +0200
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Cecil Westerhof <Cecil@decebal.nl> writes:

> Andreas Leitgeb <avl@logic.at> writes:
>
>> 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"
>
> My startup is expensive. When doing it like that I get a real around 9
> seconds, but when I use:
>     time jshell --no-startup <<< /exit
>
> real is between 1.5 and 2 seconds.
>
> I only do:
>     import java.text.DateFormat;
>     import java.text.SimpleDateFormat;
>
>
>     DateFormat dateTimeFormat = new SimpleDateFormat("yyyy-mm-dd HH:mm:ss");
>
>
>     String currentDateTime() {
>         return dateTimeFormat.format(new Date());
>     }
>
>
>     println(currentDateTime());
>
> But it seems it is quit expensive. :'-(

It is not my startup.jsh, but PRINTING.


time jshell --no-startup <<< /exit
|  Welcome to JShell -- Version 9-Debian
|  For an introduction type: /help intro

jshell> /exit
|  Goodbye

real    0m1.70s
user    0m4.43s
sys     0m0.24s
perc    275.49


time jshell --startup DEFAULT <<< /exit
|  Welcome to JShell -- Version 9-Debian
|  For an introduction type: /help intro

jshell> /exit
|  Goodbye

real    0m3.18s
user    0m8.75s
sys     0m0.38s
perc    286.75


time jshell --startup DEFAULT PRINTING <<< /exit
|  Welcome to JShell -- Version 9-Debian
|  For an introduction type: /help intro

jshell> /exit
|  Goodbye

real    0m8.51s
user    0m22.21s
sys     0m0.71s
perc    269.28


time jshell --startup DEFAULT PRINTING ~/Java/Jshell/startup.jsh <<< /exit
2019-08-29 21:08:50
|  Welcome to JShell -- Version 9-Debian
|  For an introduction type: /help intro

jshell> /exit
|  Goodbye

real    0m9.10s
user    0m22.30s
sys     0m0.63s
perc    251.98


-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof