RFR: JDK-8245168 jlink should not be treated as a "small" tool

[Magnus Ihse Bursie]

On 2020-05-18 15:16, Erik Joelsson wrote:
> Should we then add the big flags instead to have some control over 
> memory footprint, or are we trusting the default ergonomics to do the 
> right thing on every possible build system out there?
You make it sound like we shouldn't. :-) But seriously, I think we 
should have some faith in our product to actually produce good default 
values. If anything, the "small" flags were created to signal that the 
default ergonomics didn't really apply, that we favored fastest possible 
startup, at the expense of long-term performance.

  Also, this is what we do for all other tools. There is no 
"$(JAVA_TOOL_FLAGS_BIG)". Yes, I know, there is a $(JAVA_FLAGS_BIG), and 
we could of course turn it into a "TOOLS" version, but so far we have 
not done that. (The difference is that the "normal" version is supposed 
to be passed to java, like -Xmx, and the "TOOLS" version is supposed to 
be passed to tools like javac, so they are prefixed with -J like -J-Xmx.)

Are you happy with this, or do you want me to change the patch to 
include a new JAVA_TOOL_FLAGS_BIG?

/Magnus
>
> /Erik
>
> On 2020-05-18 03:12, Magnus Ihse Bursie wrote:
>> The linking of the JDK image using the jlink tool takes a 
>> considerable amount of time. However, the jlink tool is classified as 
>> a "small java" tool in the build script. This should only be used on 
>> quick small tools where a long startup time has a measurable 
>> performance impact. Clearly this does not apply to jlink.
>>
>> The effect of removing the small tool flags are most pronounced when 
>> running a slowdebug build. Robbin Ehn, which made me aware of this, 
>> reduced the running time of jlink from 36 to 21 seconds on his 
>> machine by removing the "small" flags. On a release build, the effect 
>> is much less noticeable, but it's still worth fixing.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8245168
>> Patch inline:
>> diff --git a/make/autoconf/spec.gmk.in b/make/autoconf/spec.gmk.in
>> --- a/make/autoconf/spec.gmk.in
>> +++ b/make/autoconf/spec.gmk.in
>> @@ -642,7 +642,7 @@
>>  JAVAC=@FIXPATH@ $(JAVAC_CMD)
>>  JAVADOC=@FIXPATH@ $(JAVADOC_CMD)
>>  JAR=@FIXPATH@ $(JAR_CMD)
>> -JLINK = @FIXPATH@ $(JLINK_CMD) $(JAVA_TOOL_FLAGS_SMALL)
>> +JLINK = @FIXPATH@ $(JLINK_CMD)
>>  JMOD = @FIXPATH@ $(JMOD_CMD) $(JAVA_TOOL_FLAGS_SMALL)
>>  JARSIGNER=@FIXPATH@ $(JARSIGNER_CMD)
>>  JJS=@FIXPATH@ $(JJS_CMD) $(JAVA_TOOL_FLAGS_SMALL)
>>
>> /Magnus