Revert^2 "Optimize FindClass ClassNotFoundException case"
With the current class loaders, there are many exceptions thrown for
each ClassNotFoundexception from FindClass calling
ClassLoader.loadClass. This CL reduces that by throwing directly from
FindClass to avoid these extra exceptions.
Numbers are from logging time taken by QuickDeliverException.
Time spent in exception throwing during startup goes down (Pixel 2 XL):
Camera: 20ms -> 5ms
Calculator: 5ms -> 2ms
Maps: 20ms -> 10ms
Added option -XX:FastClassNotFoundException=<bool> to enable or
disable the feature.
This reverts commit d399f579cf2a8462ef6f1fbea360fe62be174377.
Bug: 130310316
Bug: 130293184
Bug: 130209120
Test: test-art-host
Test: art/test/testrunner/testrunner.py --host --no-prebuild -t 134
Change-Id: I059abce98fe876d89de35d099647ee673c27343b
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index f123246..b793d67 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -403,7 +403,7 @@
}
}
-ClassLinker::ClassLinker(InternTable* intern_table)
+ClassLinker::ClassLinker(InternTable* intern_table, bool fast_class_not_found_exceptions)
: boot_class_table_(new ClassTable()),
failed_dex_cache_class_lookups_(0),
class_roots_(nullptr),
@@ -411,6 +411,7 @@
init_done_(false),
log_new_roots_(false),
intern_table_(intern_table),
+ fast_class_not_found_exceptions_(fast_class_not_found_exceptions),
quick_resolution_trampoline_(nullptr),
quick_imt_conflict_trampoline_(nullptr),
quick_generic_jni_trampoline_(nullptr),
@@ -2978,31 +2979,42 @@
std::string class_name_string(descriptor + 1, descriptor_length - 2);
std::replace(class_name_string.begin(), class_name_string.end(), '/', '.');
- ScopedLocalRef<jobject> class_loader_object(
- soa.Env(), soa.AddLocalReference<jobject>(class_loader.Get()));
- ScopedLocalRef<jobject> result(soa.Env(), nullptr);
- {
- ScopedThreadStateChange tsc(self, kNative);
- ScopedLocalRef<jobject> class_name_object(
- soa.Env(), soa.Env()->NewStringUTF(class_name_string.c_str()));
- if (class_name_object.get() == nullptr) {
- DCHECK(self->IsExceptionPending()); // OOME.
+ if (known_hierarchy &&
+ fast_class_not_found_exceptions_ &&
+ !Runtime::Current()->IsJavaDebuggable()) {
+ // For known hierarchy, we know that the class is going to throw an exception. If we aren't
+ // debuggable, optimize this path by throwing directly here without going back to Java
+ // language. This reduces how many ClassNotFoundExceptions happen.
+ self->ThrowNewExceptionF("Ljava/lang/ClassNotFoundException;",
+ "%s",
+ class_name_string.c_str());
+ } else {
+ ScopedLocalRef<jobject> class_loader_object(
+ soa.Env(), soa.AddLocalReference<jobject>(class_loader.Get()));
+ ScopedLocalRef<jobject> result(soa.Env(), nullptr);
+ {
+ ScopedThreadStateChange tsc(self, kNative);
+ ScopedLocalRef<jobject> class_name_object(
+ soa.Env(), soa.Env()->NewStringUTF(class_name_string.c_str()));
+ if (class_name_object.get() == nullptr) {
+ DCHECK(self->IsExceptionPending()); // OOME.
+ return nullptr;
+ }
+ CHECK(class_loader_object.get() != nullptr);
+ result.reset(soa.Env()->CallObjectMethod(class_loader_object.get(),
+ WellKnownClasses::java_lang_ClassLoader_loadClass,
+ class_name_object.get()));
+ }
+ if (result.get() == nullptr && !self->IsExceptionPending()) {
+ // broken loader - throw NPE to be compatible with Dalvik
+ ThrowNullPointerException(StringPrintf("ClassLoader.loadClass returned null for %s",
+ class_name_string.c_str()).c_str());
return nullptr;
}
- CHECK(class_loader_object.get() != nullptr);
- result.reset(soa.Env()->CallObjectMethod(class_loader_object.get(),
- WellKnownClasses::java_lang_ClassLoader_loadClass,
- class_name_object.get()));
+ result_ptr = soa.Decode<mirror::Class>(result.get());
+ // Check the name of the returned class.
+ descriptor_equals = (result_ptr != nullptr) && result_ptr->DescriptorEquals(descriptor);
}
- if (result.get() == nullptr && !self->IsExceptionPending()) {
- // broken loader - throw NPE to be compatible with Dalvik
- ThrowNullPointerException(StringPrintf("ClassLoader.loadClass returned null for %s",
- class_name_string.c_str()).c_str());
- return nullptr;
- }
- result_ptr = soa.Decode<mirror::Class>(result.get());
- // Check the name of the returned class.
- descriptor_equals = (result_ptr != nullptr) && result_ptr->DescriptorEquals(descriptor);
} else {
DCHECK(!MatchesDexFileCaughtExceptions(self->GetException(), this));
}