fix: revert span limit check from user-facing DDTrace\start_span APIs

Leiyks · Leiyks · commit bf6cd22699b6 · 2026-03-06T14:13:48.000+01:00
DDTrace\start_span() and DDTrace\start_trace_span() are user-facing
APIs that intentionally bypass the span limit — the limit applies to
auto-instrumentation (hooks) only. Guarding these APIs with
ddtrace_tracer_is_limited() broke:

- testTracerFlushedWhenSpanLimitExceeded: the test explicitly verifies
  that user-created spans work even when DD_TRACE_SPANS_LIMIT is hit.
- Guzzle integration tests: isolateTracer() uses start_trace_span()
  internally to create isolated trace contexts; when closed_spans_count
  accumulated past the limit across PHPUnit tests, no new stack was
  created and all spans in the isolated test were lost.

The curl multi code paths in handlers_curl.c and handlers_curl_php7.c
remain fixed (the actual OOM culprit reported in APMS-18744).
diff --git a/ext/ddtrace.c b/ext/ddtrace.c
@@ -3214,7 +3214,7 @@ static inline void dd_start_span(INTERNAL_FUNCTION_PARAMETERS) {
 
     ddtrace_span_data *span;
 
-    if (get_DD_TRACE_ENABLED() && !ddtrace_tracer_is_limited()) {
+    if (get_DD_TRACE_ENABLED()) {
         span = ddtrace_open_span(DDTRACE_USER_SPAN);
     } else {
         span = ddtrace_init_dummy_span();
@@ -3224,7 +3224,7 @@ static inline void dd_start_span(INTERNAL_FUNCTION_PARAMETERS) {
         span->start = (uint64_t)(start_time_seconds * ZEND_NANO_IN_SEC);
     }
 
-    if (get_DD_TRACE_ENABLED() && !ddtrace_tracer_is_limited()) {
+    if (get_DD_TRACE_ENABLED()) {
         ddtrace_observe_opened_span(span);
     }
 
@@ -3238,7 +3238,7 @@ PHP_FUNCTION(DDTrace_start_span) {
 
 /* {{{ proto string DDTrace\start_trace_span() */
 PHP_FUNCTION(DDTrace_start_trace_span) {
-    if (get_DD_TRACE_ENABLED() && !ddtrace_tracer_is_limited()) {
+    if (get_DD_TRACE_ENABLED()) {
         ddtrace_span_stack *stack = ddtrace_init_root_span_stack();
         ddtrace_switch_span_stack(stack);
         GC_DELREF(&stack->std); // We don't retain a ref to it, it's now the active_stack
