tc_create can now return NULL, throw in thread_new

also panic in moar.c if tc_create returned NULL.

src/core/threadcontext.c

@@ -10,6 +10,13 @@ MVMThreadContext * MVM_tc_create(MVMInstance *instance) {
     /* Associate with VM instance. */
     tc->instance = instance;
 
+    /* Use default loop for main thread; create a new one for others. */
+    tc->loop = instance->main_thread ? uv_loop_new() : uv_default_loop();
+    if (!tc->loop) {
+        MVM_free(tc);
+        return NULL;
+    }
+
     /* Set up GC nursery. We only allocate tospace initially, and allocate
      * fromspace the first time this thread GCs, provided it ever does. */
     tc->nursery_tospace     = MVM_calloc(1, MVM_NURSERY_SIZE);
@@ -32,13 +39,6 @@ MVMThreadContext * MVM_tc_create(MVMInstance *instance) {
     /* Allocate an initial call stack region for the thread. */
     MVM_callstack_region_init(tc);
 
-    /* Use default loop for main thread; create a new one for others. */
-    tc->loop = instance->main_thread ? uv_loop_new() : uv_default_loop();
-
-    if (!tc->loop) {
-        MVM_panic(1, "ThreadContext: could not create a new libuv loop!");
-    }
-
     /* Initialize random number generator state. */
     MVM_proc_seed(tc, (MVM_platform_now() / 10000) * MVM_proc_getpid(tc));
 

src/core/threads.c

@@ -21,8 +21,15 @@ MVMObject * MVM_thread_new(MVMThreadContext *tc, MVMObject *invokee, MVMint64 ap
     MVM_ASSIGN_REF(tc, &(thread->common.header), thread->body.invokee, invokee);
     thread->body.app_lifetime = app_lifetime;
 
-    /* Create a new thread context and set it up a little. */
+    /* Try to create the new threadcontext. Can fail if libuv can't
+     * create a loop for it for some reason (i.e. too many open files) */
     child_tc = MVM_tc_create(tc->instance);
+
+    if (!child_tc) {
+        MVM_exception_throw_adhoc(tc, "Could not create a new Thread.");
+    }
+
+    /* Set up the new threadcontext a little. */
     child_tc->thread_obj = thread;
     child_tc->thread_id = 1 + MVM_incr(&tc->instance->next_user_thread_id);
         /* Add one, since MVM_incr returns original. */

src/moar.c

@@ -77,6 +77,11 @@ MVMInstance * MVM_vm_create_instance(void) {
 
     /* Create the main thread's ThreadContext and stash it. */
     instance->main_thread = MVM_tc_create(instance);
+
+    if (!instance->main_thread) {
+        MVM_panic(1, "Could not create the main thread!");
+    }
+
     instance->main_thread->thread_id = 1;
 
     /* Next thread to be created gets ID 2 (the main thread got ID 1). */