Add db_bench with lots of column families to regression tests

Summary:
That way we can see when this graph goes up and be happy.

Couple of changes:
1. title
2. fix db_bench to delete column families before deleting the DB. this was asserting when compiled in debug mode
3. don't sync manifest when disableDataSync. We discussed this offline. I can move it to separate diff if you'd like

Test Plan: ran it

Reviewers: sdong, yhchiang, ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D22815

HISTORY.md

 # Rocksdb Change Log
 
-### Unreleased
+## Unreleased
 
 ----- Past Releases -----
 

build_tools/regression_build_test.sh

@@ -344,6 +344,38 @@ common_in_mem_args="--db=/dev/shm/rocksdb \
     --threads=32 \
     --writes_per_second=81920 > ${STAT_FILE}.seekwhilewriting_in_ram
 
+# measure fillseq with bunch of column families
+./db_bench \
+    --benchmarks=fillseq \
+    --num_column_families=500 \
+    --write_buffer_size=1048576 \
+    --db=$DATA_DIR \
+    --use_existing_db=0 \
+    --num=$NUM \
+    --writes=$NUM \
+    --open_files=55000 \
+    --statistics=1 \
+    --histogram=1 \
+    --disable_data_sync=1 \
+    --disable_wal=1 \
+    --sync=0  > ${STAT_FILE}.fillseq_lots_column_families
+
+# measure overwrite performance with bunch of column families
+./db_bench \
+    --benchmarks=overwrite \
+    --num_column_families=500 \
+    --write_buffer_size=1048576 \
+    --db=$DATA_DIR \
+    --use_existing_db=1 \
+    --num=$NUM \
+    --writes=$((NUM / 10)) \
+    --open_files=55000 \
+    --statistics=1 \
+    --histogram=1 \
+    --disable_data_sync=1 \
+    --disable_wal=1 \
+    --sync=0 \
+    --threads=8 > ${STAT_FILE}.overwrite_lots_column_families
 
 # send data to ods
 function send_to_ods {
@@ -392,3 +424,5 @@ send_benchmark_to_ods readrandom memtablereadrandom $STAT_FILE.memtablefillreadr
 send_benchmark_to_ods readwhilewriting readwhilewriting $STAT_FILE.readwhilewriting
 send_benchmark_to_ods readwhilewriting readwhilewriting_in_ram ${STAT_FILE}.readwhilewriting_in_ram
 send_benchmark_to_ods seekrandomwhilewriting seekwhilewriting_in_ram ${STAT_FILE}.seekwhilewriting_in_ram
+send_benchmark_to_ods fillseq fillseq_lots_column_families ${STAT_FILE}.fillseq_lots_column_families
+send_benchmark_to_ods overwrite overwrite_lots_column_families ${STAT_FILE}.overwrite_lots_column_families

db/db_bench.cc

@@ -1110,6 +1110,8 @@ class Benchmark {
   }
 
   ~Benchmark() {
+    std::for_each(db_.cfh.begin(), db_.cfh.end(),
+                  [](ColumnFamilyHandle* cfh) { delete cfh; });
     delete db_.db;
     delete prefix_extractor_;
   }
@@ -1334,6 +1336,8 @@ class Benchmark {
           method = nullptr;
         } else {
           if (db_.db != nullptr) {
+            std::for_each(db_.cfh.begin(), db_.cfh.end(),
+                          [](ColumnFamilyHandle* cfh) { delete cfh; });
             delete db_.db;
             db_.db = nullptr;
             db_.cfh.clear();