The cachetable-simple-pin-noblocking-cheap test occasionally fails du…

…e to a TOKUDB_TRY_AGAIN error being kicked out of the cachetable to the test. The test does not expect this error so it crashes. The TOKUDB_TRY_AGAIN error was caused by a locking conflict between the test and the cachetable evictor which periodically runs on a background thread. Since the evictor is not an important part of this test, its execution was removed by setting the cachetable size larger than the test's cachetable footprint.

Tools:
Ubuntu 18.04
gcc 7.3.0
Cmake 3.10.2

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ft/tests/cachetable-simple-pin-nonblocking-cheap.cc

@@ -107,7 +107,11 @@ run_case_that_should_fail(CACHEFILE f1, pair_lock_type first_lock, pair_lock_typ
 
 static void
 run_test (void) {
-    const int test_limit = 12;
+    // sometimes the cachetable evictor runs during the test.  this sometimes causes cachetable pair locking contention,
+    // which results with a TOKUDB_TRY_AGAIN error occurring.  unfortunately, the test does not expect this and fails.
+    // set cachetable size limit to a value big enough so that the cachetable evictor is not triggered during the test.
+    const int test_limit = 100;
+
     int r;
     CACHETABLE ct;
     toku_cachetable_create(&ct, test_limit, ZERO_LSN, nullptr);