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Merge branch 'java-director-leak'

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* java-director-leak:
  Cosmetic tidyup in SWIG_JAVA_DETACH_ON_THREAD_END code
  Java: Move auxiliary methods into JObjectWrapper.
  Java: Option to detach from the JVM in the thread destructor.

Conflicts:
	CHANGES.current
This commit is contained in:
William S Fulton 2022-05-28 10:24:08 +01:00
commit 1d6f4b4eae
2 changed files with 42 additions and 1 deletions
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33
Lib/java/director.swg
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@ -51,6 +51,10 @@ SWIGINTERN int Swig::GetThreadName(char *name, size_t len) {
#endif
#if defined(SWIG_JAVA_DETACH_ON_THREAD_END)
#include <pthread.h>
#endif
namespace Swig {
/* Java object wrapper */
@ -133,6 +137,19 @@ namespace Swig {
}
}
#if defined(SWIG_JAVA_DETACH_ON_THREAD_END)
static void detach(void *jvm) {
static_cast<JavaVM *>(jvm)->DetachCurrentThread();
}
static void make_detach_key() {
pthread_key_create(&detach_key_, detach);
}
/* thread-local key to register a destructor */
static pthread_key_t detach_key_;
#endif
private:
/* pointer to Java object */
jobject jthis_;
@ -140,6 +157,10 @@ namespace Swig {
bool weak_global_;
};
#if defined(SWIG_JAVA_DETACH_ON_THREAD_END)
pthread_key_t JObjectWrapper::detach_key_;
#endif
/* Local JNI reference deleter */
class LocalRefGuard {
JNIEnv *jenv_;
@ -201,9 +222,19 @@ namespace Swig {
#else
director_->swig_jvm_->AttachCurrentThread(jenv, &args);
#endif
#if defined(SWIG_JAVA_DETACH_ON_THREAD_END)
// At least on Android 6, detaching after every call causes a memory leak.
// Instead, register a thread desructor and detach only when the thread ends.
// See https://developer.android.com/training/articles/perf-jni#threads
static pthread_once_t once = PTHREAD_ONCE_INIT;
pthread_once(&once, JObjectWrapper::make_detach_key);
pthread_setspecific(JObjectWrapper::detach_key_, director->swig_jvm_);
#endif
}
~JNIEnvWrapper() {
#if !defined(SWIG_JAVA_NO_DETACH_CURRENT_THREAD)
#if !defined(SWIG_JAVA_DETACH_ON_THREAD_END) && !defined(SWIG_JAVA_NO_DETACH_CURRENT_THREAD)
// Some JVMs, eg jdk-1.4.2 and lower on Solaris have a bug and crash with the DetachCurrentThread call.
// However, without this call, the JVM hangs on exit when the thread was not created by the JVM and creates a memory leak.
if (env_status == JNI_EDETACHED)