Import wiredtiger: 4eb9f719eed3e24a9e49a6fa60d8d56eadb8b189 from branch mongodb-4.4

ref: d198ee319d..4eb9f719ee
for: 4.5.1

WT-5801       Reduce runtime of Python unit tests by pruning test_compat02.py
WT-6276       Add size first to cache and btree to avoid the race that can cause cache size underflow
WT-6342       Fix external symbolizer path for PPC Evergreen tasks
WT-6366       Off-by-one overflow in block-modification bitmaps for incremental backup
WT-6373       Don't reset transaction ids when evicting mixed mode transactions
WT-6376       Minor cleanups in resolving prepared operations
WT-6378       Fix compile failure on OS X 10.12

1 files changed, 12 insertions, 7 deletions

diff --git a/src/third_party/wiredtiger/test/csuite/incr_backup/main.c b/src/third_party/wiredtiger/test/csuite/incr_backup/main.c
index 68a4e4b26d1..fee64ff683a 100644
--- a/src/third_party/wiredtiger/test/csuite/incr_backup/main.c
+++ b/src/third_party/wiredtiger/test/csuite/incr_backup/main.c
@@ -479,6 +479,7 @@ base_backup(WT_CONNECTION *conn, WT_RAND_STATE *rand, const char *home, const ch
     int nfiles, ret;
     char buf[4096];
     char *filename;
+    char granularity_unit;
 
     nfiles = 0;
 
@@ -493,14 +494,18 @@ base_backup(WT_CONNECTION *conn, WT_RAND_STATE *rand, const char *home, const ch
     testutil_check(conn->open_session(conn, NULL, NULL, &session));
     tinfo->full_backup_number = tinfo->incr_backup_number++;
 
-    /* Half of the runs with a low granularity: 1M */
-    if (__wt_random(rand) % 2 == 0)
-        granularity = 1;
-    else
-        granularity = 1 + __wt_random(rand) % 20;
+    /* Half of the runs with very low granularity to stress bitmaps */
+    granularity = __wt_random(rand) % 20;
+    if (__wt_random(rand) % 2 == 0) {
+        granularity_unit = 'K';
+        granularity += 4;
+    } else {
+        granularity_unit = 'M';
+        granularity += 1;
+    }
     testutil_check(__wt_snprintf(buf, sizeof(buf),
-      "incremental=(granularity=%" PRIu32 "M,enabled=true,this_id=ID%d)", granularity,
-      (int)tinfo->full_backup_number));
+      "incremental=(granularity=%" PRIu32 "%c,enabled=true,this_id=ID%d)", granularity,
+      granularity_unit, (int)tinfo->full_backup_number));
     VERBOSE(3, "open_cursor(session, \"backup:\", NULL, \"%s\", &cursor)\n", buf);
     testutil_check(session->open_cursor(session, "backup:", NULL, buf, &cursor));