| Eclipse Java Compiler for on-fly java compilation is slow [message #1075925] |
Tue, 30 July 2013 10:41  |
 Alexey M
Messages: 1
Registered: July 2013 |
Junior Member |
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Hi all,
we are using Eclipse Java Compiler (ejc 3.5.1) for on-fly compilation of java files. We compile single file using our two jars in additional classpath. Here is an example of our call:
JavaCompiler compiler = new EclipseCompiler();
ClassFileManager fileManager = new ClassFileManager(null, null);
LOG.info("Classpath: " + classPath);
fileManager.handleOption("-classpath", additionalLibs.iterator());
DiagnosticCollector<JavaFileObject> diagnostics = new DiagnosticCollector<JavaFileObject>();
List<? extends JavaFileObject> files = Collections.singletonList(new CharSequenceJavaFileObject(className, src));
boolean result = compiler.getTask(new OutputStreamWriter(new NullOutputStream()), fileManager, diagnostics, optionList, null, files).call();
if (result) {
return fileManager.getJavaClassObject().getBytes();
} else {
...
}
We compile each file in separate task because we have a custom classloader that tries to find class and if it is not available, it runs compilation using ecj (code is fetched from storage) and builds class based of received bytecode.
So during the first execution we need to compile about hundred of classes and it looks slow. Compilation of a single file takes 0.5-1 sec. I run it with profiler: i.imgur.com/UHySdLo.png
Here is a call stack to the longest isPackage function:
at org.eclipse.jdt.internal.compiler.batch.ClasspathJar.isPackage(ClasspathJar.java:147)
at org.eclipse.jdt.internal.compiler.batch.ClasspathJar.findClass(ClasspathJar.java:93)
at org.eclipse.jdt.internal.compiler.batch.FileSystem.findClass(FileSystem.java:242)
at org.eclipse.jdt.internal.compiler.batch.FileSystem.findType(FileSystem.java:334)
at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.createPackage(LookupEnvironment.java:700)
at org.eclipse.jdt.internal.compiler.lookup.CompilationUnitScope.buildTypeBindings(CompilationUnitScope.java:89)
at org.eclipse.jdt.internal.compiler.lookup.LookupEnvironment.buildTypeBindings(LookupEnvironment.java:152)
at org.eclipse.jdt.internal.compiler.Compiler.internalBeginToCompile(Compiler.java:717)
at org.eclipse.jdt.internal.compiler.Compiler.beginToCompile(Compiler.java:377)
at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:426)
at org.eclipse.jdt.internal.compiler.batch.Main.performCompilation(Main.java:3687)
at org.eclipse.jdt.internal.compiler.tool.EclipseCompilerImpl.call(EclipseCompilerImpl.java:69)
at org.eclipse.jdt.internal.compiler.tool.EclipseCompiler$1.call(EclipseCompiler.java:181)
Looks like it this function is small, but it is called 9.5M times for 250 compilations of single file, having two our jars in classpath. Is it possible somehow to improve performance of this compilation, or the only solution is to compile all files in one run?
Thanks.
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