The total physical memory of 3GB iOS devices is very tight. After system memory occupation, the available memory for third-party apps is extremely insufficient, leading to frequent OOM termination. Enabling or disabling JavaScriptCore causes a huge difference in app memory crash threshold. Without JSC, the app will crash at only 1.52GB memory usage, which severely restricts normal business running. The common 4MB and 8MB memory allocation used in our project falls into the high memory fragmentation range defined by libmalloc, resulting in the lowest memory crash limit and worst stability. Our core business relies heavily on JSC environment for JS interaction, resource rendering and dynamic logic execution. We cannot shut down JSC, but 3GB devices still face serious memory shortage even with JSC enabled. Mass users with 3GB RAM old iOS devices suffer from frequent app crashes, freeze, background kill and loading failure, which badly damage user experience and product reputation. We have finished all app-level memory optimization: adjust allocation size, optimize memory release, reduce resident memory, but still cannot break through the fixed memory crash limit. There is no effective solution on application layer. We sincerely ask Apple official engineers to provide official suggestions, system-level memory tuning solutions and JSC memory scheduling optimization guidance to solve the memory limit bottleneck on 3GB RAM iOS devices.

I think that it would be helpful to have better interoperability between Swift and JavaScript. There are a lot of useful packages on NPM that don't have equivalents for Swift. It would be helpful if Apple provided easier ways to use NPM packages in a Swift project. Currently, the JavaScriptCore framework is missing many standard things used in many packages, like the fetch API. It would be helpful to be able to run sandboxed JavaScript code inside of a Swift app but allow access to specific domains, folders, etc., using a permissions system similar to Deno.

I have a transformation function that takes in data, executes some instructions, and returns an output. This function is dynamic and not shipped with the binary. Currently, I’m executing it using JavaScriptCore.JSContext, which works well, but the function itself is written in JavaScript. Is there a way to achieve something similar using Swift – such as executing a dynamic Swift script, either directly or through other means? I know this is possible on macOS, but I’m not sure about iOS. I’ve also heard that extensions might open up some possibilities here. Any insights or alternative approaches would be appreciated.

Hi there, I'm experiencing several crashes on JavaScriptCore pas_panic_on_out_of_memory_error, only on devices with tvOS 15.4 and 15.4.1. This happens with users using the app for several hours as well as 5 seconds after launching the app. Devices: AppleTV6,2 and AppleTV5,3 Thread 14 — JavaScriptCore pas_panic_on_out_of_memory_error (JavaScriptCore) JavaScriptCore bmalloc_try_iso_allocate_impl_impl_slow (JavaScriptCore) JavaScriptCore bmalloc_heap_config_specialized_local_allocator_try_allocate_small_segregated_slow (JavaScriptCore) JavaScriptCore bmalloc_allocate_impl_casual_case (JavaScriptCore) JavaScriptCore ***::String::String(char16_t const*, unsigned int) (JavaScriptCore) JavaScriptCore JSC::LiteralParser<char16_t>::parsePrimitiveValue(JSC::VM&) (JavaScriptCore) JavaScriptCore JSC::LiteralParser<char16_t>::parse(JSC::ParserState) (JavaScriptCore) JavaScriptCore JSC::jsonProtoFuncParse(JSC::JSGlobalObject*, JSC::CallFrame*) (JavaScriptCore) JavaScriptCore llint_entry (JavaScriptCore) JavaScriptCore llint_entry (JavaScriptCore) JavaScriptCore llint_entry (JavaScriptCore) JavaScriptCore llint_entry (JavaScriptCore) JavaScriptCore vmEntryToJavaScript (JavaScriptCore) JavaScriptCore JSC::Interpreter::executeCall(JSC::JSGlobalObject*, JSC::JSObject*, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (JavaScriptCore) JavaScriptCore JSC::boundThisNoArgsFunctionCall(JSC::JSGlobalObject*, JSC::CallFrame*) (JavaScriptCore) JavaScriptCore vmEntryToNative (JavaScriptCore) JavaScriptCore JSC::Interpreter::executeCall(JSC::JSGlobalObject*, JSC::JSObject*, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (JavaScriptCore) JavaScriptCore JSC::profiledCall(JSC::JSGlobalObject*, JSC::ProfilingReason, JSC::JSValue, JSC::CallData const&, JSC::JSValue, JSC::ArgList const&) (JavaScriptCore) JavaScriptCore JSObjectCallAsFunction (JavaScriptCore) JavaScriptCore -[JSValue invokeMethod:withArguments:] (JavaScriptCore) ITMLKit -[IKJSObject invokeMethod:withArguments:] (ITMLKit) ITMLKit -[IKJSEventListenerObject invokeMethod:withArguments:thenDispatchEvent:extraInfo:] (ITMLKit) ITMLKit __43-[IKJSXMLHTTPRequest setRequestReadyState:]_block_invoke (ITMLKit) ITMLKit -[IKAppContext _doEvaluate:] (ITMLKit) ITMLKit -[IKAppContext _evaluate:] (ITMLKit) ITMLKit __41-[IKAppContext evaluate:completionBlock:]_block_invoke (ITMLKit) ITMLKit -[IKAppContext _sourcePerform] (ITMLKit) ITMLKit -[IKConcurrentEvaluator lockSchedulingForEvaluation:] (ITMLKit) ITMLKit IKRunLoopSourcePerformCallBack (ITMLKit) CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ (CoreFoundation) CoreFoundation __CFRunLoopDoSource0 (CoreFoundation) CoreFoundation __CFRunLoopDoSources0 (CoreFoundation) CoreFoundation __CFRunLoopRun (CoreFoundation) CoreFoundation CFRunLoopRunSpecific (CoreFoundation) ITMLKit -[IKAppContext _jsThreadMain] (ITMLKit) Foundation __NSThread__start__ (Foundation) libsyste...ad.dylib _pthread_start (libsystem_pthread.dylib) libsyste...ad.dylib thread_start (libsystem_pthread.dylib) This issue seems very similar to this existing thread, although not sure its related

Hi, My app is using JavascriptCore to run the business logic in a javascript environment. We are randomly seeing crashes when users move the app back to the foreground. These crashes are reported by Firebase (I am attaching an example). I also tried to find them in Organizer, but the stacktraces don't match and I am not sure if they are pointing to the same error (I attach one just in case). I was trying to investigate a little bit about this, but I could find any explanation about what pas_reallocation_did_fail would mean. Here is our implementation: -(void) enqueueCallback:(JSValue *)callback withArguments:(NSArray *)args exclusive:(BOOL)exclusive { [self enqueueBlock:^{ @autoreleasepool { [callback callWithArguments:args]; } } exclusive:exclusive]; } Basically, every JS block is enqueued and then run by a dedicated thread specific to our JSContext. Can I get some help? Thanks in advance! Crashlytics.txt 2024-08-30_10-00-01.2572_-0400-f757f8306eda9679ec1b2ff90fbc66c4eb1fbee7.crash