RFR: 8236075: Minor bootstrap improvements

[Mandy Chung]

Hi Claes,

On 1/20/20 7:54 AM, Claes Redestad wrote:
> Hi,
>
> some minor cleanups and enhancements in and around java.lang.ClassLoader
> which add up to a small startup improvement:
>
> - Remove use of Vector/Hashtable from ClassLoader, along with a few
>   other improvements/modernizations.
> - Refactor ClassLoader::sys_paths/user_paths so that they're initialized
> lazily but also published safely
>
> Webrev: http://cr.openjdk.java.net/~redestad/8236075/open.01/
> Bug:    https://bugs.openjdk.java.net/browse/JDK-8236075

This patch looks okay in general.   Below are some small comments:

ClassLoaderHelper.java
    Moving ClassLoader::initializePath path-parsing method to 
ClassLoaderHelper is okay while duplicating the code in macOS and unix 
CLH implementation is less ideal.   One option to consider is to add a 
utility method in a shared class like parsePath(String paths, boolean 
allowQuote).

OTOH, it's also okay to me since this duplicated code is small for now 
that we can follow up as part of the native library handling refactoring 
I'm working on.  But I will suggest to use the same pathStart and 
pathEnd variable names as in the windows implementation.

StaticProperty.java
      I believe "java.library.path" and "sun.boot.library.path" are 
always set to non-null.  Since the existing code assumes them that may 
be null, I agree with you to keep the existing logic as we discussed.   
We will follow up this later.

You added getProperty(Properties props, String key).   Do you see the 
change to replace System.getProperty calls with one single call to 
System.getProperties and Properties.getProperty is significant to 
performance?   i.e.  what if you keep the static method to 
getProperty(String key) (was initProperty before your patch) and  add 
getProperty(String key, String defaultValue) where the defaultValue may 
be null.

Mandy