Bug#30766089 8.0.17: SEVERE REGRESSION IN PERFORMANCE OF SELECT COUNT(*) FROM

LARGE TABLE WITH LOB

PB2-fix: Fix the test failure in test main.kill_debug in PB2.

The issue was that a debug statement set by the test wasn't being executed
because we'd disabled the read ahead code and the debug statement was executed
here. It has now been moved to the main thread.

Approved-by: Sunny Bains <sunny.bains@oracle.com>

Author: Darshan M N

storage/innobase/row/row0pread.cc

@@ -1052,8 +1052,6 @@ dberr_t Parallel_reader::Scan_ctx::create_contexts(const Ranges &ranges) {
 }
 
 void Parallel_reader::read_ahead_worker(page_no_t n_pages) {
-  DBUG_EXECUTE_IF("bug28079850", set_error_state(DB_INTERRUPTED););
-
   while (is_active() && !is_error_set()) {
     uint64_t dequeue_count{};
 
@@ -1161,6 +1159,8 @@ void Parallel_reader::parallel_read() {
     read_ahead();
   }
 
+  DBUG_EXECUTE_IF("bug28079850", set_error_state(DB_INTERRUPTED););
+
   /* Don't wait for the threads to finish if the read is not synchronous. */
   if (!m_sync) {
     return;