[Getting warning while running db_crashtest]

Summary:
When I run db_crashtest, I am seeing lot of warnings that say db_stress completed
before it was killed. To fix that I made ops per thread a very large value so that it keeps
running until it is killed.

I also set #reopens to 0. Since we are killing the process anyway, the 'simulated crash'
that happens during reopen may not add additional value.

I usually see 10-25K ops happening before the kill. So I increased max_key from 100 to
1000 so that we use more distinct keys.

Test Plan:
Ran a few times.

Revert Plan: OK

Task ID: #

Reviewers: emayanke

Reviewed By: emayanke

CC: leveldb

Differential Revision: https://reviews.facebook.net/D9909

tools/db_crashtest.py

@@ -25,7 +25,8 @@ def main(argv):
     interval = 120  # time for one db_stress instance to run
     duration = 6000  # total time for this script to test db_stress
     threads = 32
-    ops_per_thread = 500000
+    # since we will be killing anyway, use large value for ops_per_thread
+    ops_per_thread = 10000000
     write_buf_size = 4 * 1024 * 1024
 
     for opt, arg in opts:
@@ -62,10 +63,10 @@ def main(argv):
                         --ops_per_thread=0' + str(ops_per_thread) + ' \
                         --threads=0' + str(threads) + ' \
                         --write_buffer_size=' + str(write_buf_size) + '\
-                        --reopen=10 \
+                        --reopen=0 \
                         --readpercent=50 \
                         --db=/tmp/rocksdb/crashtest \
-                        --max_key=100'], stderr=subprocess.PIPE, shell=True)
+                        --max_key=1000'], stderr=subprocess.PIPE, shell=True)
         time.sleep(interval)
         while True:
             if time.time() > killtime: