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JSVM-API常见问题
定位方法
程序崩溃类问题:通过C++崩溃时调用栈查询FAQ的方式定位代码问题
程序执行结果不符合预期类问题:需应用通过JSVM-API调用返回值定位到执行失败或执行结果不符合预期的位置,通过函数名查询FAQ
程序崩溃类
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Q:在OH_JSVM_RunScript或OH_JSVM_CallFunction时crash,调用栈顶层为SetReturnValue
#00 pc 0000000000c68ef0 /system/lib64/ndk/libjsvm.so(v8impl::(anonymous namespace)::FunctionCallbackWrapper::SetReturnValue(JSVM_Value__*)+16) #01 pc 0000000000c5ad30 /system/lib64/ndk/libjsvm.so(v8impl::(anonymous namespace)::FunctionCallbackWrapper::Invoke(v8::FunctionCallbackInfo<v8::Value> const&)+332) #02 pc 00000000014a9e58 /system/lib64/ndk/libjsvm.so #03 pc 00000000014a95d4 /system/lib64/ndk/libjsvm.so(v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*)+176) #04 pc 0000000000f7dab4 /system/lib64/ndk/libjsvm.so(Builtins_CEntry_Return1_ArgvOnStack_BuiltinExit+84) #05 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #06 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #07 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #08 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #09 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #10 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #11 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #12 pc 0000000000eece40 /system/lib64/ndk/libjsvm.so(Builtins_InterpreterEntryTrampoline+288) #13 pc 0000000000fe09f4 /system/lib64/ndk/libjsvm.so(Builtins_PromiseFulfillReactionJob+52) #14 pc 0000000000f155c0 /system/lib64/ndk/libjsvm.so(Builtins_RunMicrotasks+672) #15 pc 0000000000eeab54 /system/lib64/ndk/libjsvm.so(Builtins_JSRunMicrotasksEntry+148) #16 pc 00000000015bed78 /system/lib64/ndk/libjsvm.so(v8::internal::(anonymous namespace)::Invoke(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&)+2520) #17 pc 00000000015bf50c /system/lib64/ndk/libjsvm.so(v8::internal::(anonymous namespace)::InvokeWithTryCatch(v8::internal::Isolate*, v8::internal::(anonymous namespace)::InvokeParams const&)+104) #18 pc 00000000015bf730 /system/lib64/ndk/libjsvm.so(v8::internal::Execution::TryRunMicrotasks(v8::internal::Isolate*, v8::internal::MicrotaskQueue*)+80) #19 pc 00000000015ecf4c /system/lib64/ndk/libjsvm.so(v8::internal::MicrotaskQueue::RunMicrotasks(v8::internal::Isolate*)+312) #20 pc 00000000015ecd9c /system/lib64/ndk/libjsvm.so(v8::internal::MicrotaskQueue::PerformCheckpointInternal(v8::Isolate*)+52) #21 pc 00000000015deaa0 /system/lib64/ndk/libjsvm.so(v8::internal::Isolate::FireCallCompletedCallbackInternal(v8::internal::MicrotaskQueue*)+280) #22 pc 00000000014334e8 /system/lib64/ndk/libjsvm.so(v8::CallDepthScope<true>::~CallDepthScope()+248) #23 pc 00000000014330a4 /system/lib64/ndk/libjsvm.so(v8::Script::Run(v8::Local<v8::Context>, v8::Local<v8::Data>)+884) #24 pc 0000000000c5c2ac /system/lib64/ndk/libjsvm.so(OH_JSVM_RunScript+272)A:SetReturnValue用于设置js函数的返回值,在js完成注入的native函数调用后触发。需检查native函数的返回值是否正确,如返回值(类型JSVM_Value)是否未初始化就直接返回。
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Q:js执行虚拟机初始化注入的native函数时程序崩溃
A:检查JSVM_CallbackStruct是否为栈上变量,跨函数使用时需保证JSVM_CallbackStruct生命周期 >JSVM_Env的生命周期
func { // ... JSVM_CallbackStruct param[] = { {.data = nullptr, .callback = ConsoleInfo}, {.data = nullptr, .callback = Add}, }; JSVM_PropertyDescriptor descriptor[] = { {"consoleinfo", NULL, ¶m[0], NULL, NULL, NULL, JSVM_DEFAULT}, {"add", NULL, ¶m[1], NULL, NULL, NULL, JSVM_DEFAULT}, }; // create env, register native method, and open env scope JSVM_Env env; OH_JSVM_CreateEnv(vm, sizeof(descriptor) / sizeof(descriptor[0]), descriptor, &env); // ... OH_JSVM_DestroyEnv(env); // ... }样例中的代码结构如上,JS引擎实例在函数结束前被关闭,所以可以直接使用栈上的param。
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Q:OH_JSVM_ReferenceRef、OH_JSVM_ReferenceUnRef、OH_JSVM_CreateReference、OH_JSVM_DeleteReference时程序崩溃
A:检查是否同时有多个线程持有和释放JSVM_Ref,见 多线程共享引擎实例
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Q:在虚拟机引擎实例中创建JS类型实例崩溃(如OH_JSVM_CreateDouble),调用栈如下
#00 pc 0000000001d209e4/system/1ib64/ndk/libjsvm.so(v8::base::0S::Abort()+28) #01 pc 0000000001408480/system/lib64/ndk/libjsvm.so(v8::Utils::ReportApiFailure(char const*,char const*)+124) #02 pc 00000000015c99b8/system/lib64/ndk/libjsvm.so(v8::internal::Handlescope::Extend(v8::internal::Isolate*+200)A:检查HandleScope的使用是否正确,见生命周期管理
JSVM-API执行失败类
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Q:OH_JSVM_GetCbInfo的无法获取JS函数参数
A:检查函数传递的参数是否正确,见获取JS传入参数及其数量
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Q:OH_JSVM_CreateFunction等函数调用失败,返回值为JSVM_PENDING_EXCEPTION
A:JSVM_PENDING_EXCEPTION表明当前虚拟机环境中存在未处理的异常,可能是由于本次调用产生的JS异常,也可能是之前调用产生的未被清理的异常。可以通过在函数调用前插入OH_JSVM_GetAndClearLastException排查之前是否有未清除的异常。如果为之前的未清理异常,检查是否有JSVM接口调用未处理异常返回值;如未本次产生的异常,需清理异常,避免影响后续的函数调用。获取并清理异常的函数为OH_JSVM_GetAndClearLastException
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Q:JS执行时无法找到 OH_JSVM_DefineClass 定义的类
A:检查是否将定义的类绑定到上下文中,见上下文绑定对象
JSVM-API内存管理类
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Q:调用OH_JSVM_ReferenceUnRef将引用计数减到0后,再调用OH_JSVM_DeleteReference删除引用,为什么该引用所占用的Native内存没有被立即释放?
A:当引用计数通过OH_JSVM_ReferenceUnRef减到0后,该引用会被置为虚引用,此时调用OH_JSVM_DeleteReference并不会立即释放内存,而是将内存释放交给JS对象的垃圾回收器(GC)处理,当JS对象被GC回收时,会触发回调函数来释放该对象对应的Native内存资源,由于GC的触发需要满足特定条件,因此内存释放可能会有一定的延迟。如果对内存管理有实时性要求,则须避免将引用计数减到0。


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