Proposed fix: buildscript java version detection fails on Linux/Ubuntu on Picked up JAVA_TOOL_OPTIONS

[Kevin Rushforth]

I will also note that OpenJFX depends on OpenJDK, so I am fine using 
"-fullversion" as long as it works in both OpenJDK and Oracle JDK 
builds, and both before and after the version string changes in JEP-223.

-- Kevin


David DeHaven wrote:
> I can't comment on non-Oracle JDKs, but It's in libjli so anything based on OpenJDK should support it.
>
> -DrD-
>
>   
>> I was not aware of the existence of the -fullversion option. It is not listed at the Oracle site, afaik. Can it be assumed to be present in non-OpenJDK, non-Oracle JDKs?
>>
>> David DeHaven schreef op 2015-08-26 15:38:
>>     
>>>> The gradle build tries to find the version of the used Java JDK by running 'java -version', skipping the first line and expects to find the version in the second line.
>>>> However, on Linux (Ubuntu) the first line of *any* Java invocation is "Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar"[1], thus failing at detection of the version, aborting the build.
>>>> The 'Pickup up...' line is a standard feature of the JDK and a legacy that doesn't seem to be removed soon[2].
>>>> I guess the build script needs to accommodate for this.
>>>> Proposed fix:
>>>> // Determine the verion of Java in JDK_HOME. It looks like this:
>>>> //
>>>> // $ java -version
>>>> // Picked up JAVA_TOOL_OPTIONS: -javaagent:/usr/share/java/jayatanaag.jar
>>>> // java version "1.7.0_45"
>>>> // Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
>>>> // Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)
>>>> //
>>>> // The first line is optional, we need to parse the third line
>>>> def inStream = new java.io.BufferedReader(new java.io.InputStreamReader(new java.lang.ProcessBuilder(JAVA, "-version").start().getErrorStream()));
>>>> try {
>>>>   String v = inStream.readLine();
>>>>   if (v != null) {
>>>> 	if (v.startsWith("Picked up")) {
>>>> 	   inStream.readLine();
>>>> 	}
>>>>       v = inStream.readLine();
>>>>         
>>> Why not just use "java -fullversion" instead?
>>> $ java -fullversion
>>> java full version "1.8.0_60-ea-b14"
>>> $ JAVA_TOOL_OPTIONS="-Xmx512M" java -fullversion
>>> java full version "1.8.0_60-ea-b14"
>>> $ java -version
>>> java version "1.8.0_60-ea"
>>> Java(TM) SE Runtime Environment (build 1.8.0_60-ea-b14)
>>> Java HotSpot(TM) 64-Bit Server VM (build 25.60-b14, mixed mode)
>>> $ JAVA_TOOL_OPTIONS="-Xmx512M" java -version
>>> Picked up JAVA_TOOL_OPTIONS: -Xmx512M
>>> java version "1.8.0_60-ea"
>>> Java(TM) SE Runtime Environment (build 1.8.0_60-ea-b14)
>>> Java HotSpot(TM) 64-Bit Server VM (build 25.60-b14, mixed mode)
>>> It's a lot less stuff to parse. Also, "java -fullversion" does not
>>> start the VM, so should be faster.
>>> -DrD-
>>>       
>
>