Temporarily disable snapshot list refresh for atomic flush stress test (#5581)

Summary:
Atomic flush test started to fail after https://github.com/facebook/rocksdb/issues/5099. Then https://github.com/facebook/rocksdb/issues/5278 provided a fix after
which the same error occurred much less frequently. However it still occur
occasionally. Not sure what the root cause is. This PR disables the feature of
snapshot list refresh, and we should keep an eye on the failure in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5581

Differential Revision: D16295985

Pulled By: riversand963

fbshipit-source-id: c9e62e65133c52c21b07097de359632ca62571e4

tools/db_crashtest.py

@@ -141,6 +141,7 @@ atomic_flush_params = {
     "write_buffer_size": 1024 * 1024,
     # disable pipelined write when test_atomic_flush is true
     "enable_pipelined_write": 0,
+    "snap_refresh_nanos": 0,
 }
 
 

tools/db_stress.cc

@@ -512,6 +512,10 @@ DEFINE_uint64(num_iterations, 10, "Number of iterations per MultiIterate run");
 static const bool FLAGS_num_iterations_dummy __attribute__((__unused__)) =
     RegisterFlagValidator(&FLAGS_num_iterations, &ValidateUint32Range);
 
+DEFINE_uint64(
+    snap_refresh_nanos, 100 * 1000 * 1000,
+    "If non-zero, compactions will periodically refresh snapshot list.");
+
 namespace {
 enum rocksdb::CompressionType StringToCompressionType(const char* ctype) {
   assert(ctype);
@@ -2724,6 +2728,8 @@ class StressTest {
         fprintf(stdout, "  %s\n", p.c_str());
       }
     }
+    fprintf(stdout, "Snapshot refresh nanos    : %" PRIu64 "\n",
+            FLAGS_snap_refresh_nanos);
 
     fprintf(stdout, "------------------------------------------------\n");
   }
@@ -2873,6 +2879,7 @@ class StressTest {
     } else {
       options_.merge_operator = MergeOperators::CreatePutOperator();
     }
+    options_.snap_refresh_nanos = FLAGS_snap_refresh_nanos;
 
     fprintf(stdout, "DB path: [%s]\n", FLAGS_db.c_str());