Summary:
This change improves the performance of iterators doing long range scans (e.g. big/full table scans in MyRocks) by using readahead and prefetching additional data on each disk IO. This prefetching is automatically enabled on noticing more than 2 IOs for the same table file during iteration. The readahead size starts with 8KB and is exponentially increased on each additional sequential IO, up to a max of 256 KB. This helps in cutting down the number of IOs needed to complete the range scan.
Constraints:
- The prefetched data is stored by the OS in page cache. So this currently works only for non direct-reads use-cases i.e applications which use page cache. (Direct-I/O support will be enabled in a later PR).
- This gets currently enabled only when ReadOptions.readahead_size = 0 (which is the default value).
Thanks to siying for the original idea and implementation.
**Benchmarks:**
Data fill:
```
TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=fillrandom -num=1000000000 -compression_type="none" -level_compaction_dynamic_level_bytes
```
Do a long range scan: Seekrandom with large number of nexts
```
TEST_TMPDIR=/data/users/$USER/benchmarks/iter ./db_bench -benchmarks=seekrandom -duration=60 -num=1000000000 -use_existing_db -seek_nexts=10000 -statistics -histogram
```
Page cache was cleared before each experiment with the command:
```
sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"
```
```
Before:
seekrandom : 34020.945 micros/op 29 ops/sec; 32.5 MB/s (1636 of 1999 found)
With this change:
seekrandom : 8726.912 micros/op 114 ops/sec; 126.8 MB/s (5702 of 6999 found)
```
~3.9X performance improvement.
Also verified with strace and gdb that the readahead size is increasing as expected.
```
strace -e readahead -f -T -t -p <db_bench process pid>
```
Closes https://github.com/facebook/rocksdb/pull/3282
Differential Revision: D6586477
Pulled By: sagar0
fbshipit-source-id: 8a118a0ed4594fbb7f5b1cafb242d7a4033cb58c
Summary:
The default changed in 6a14f7a976 but this comment was not updated.
Closes https://github.com/facebook/rocksdb/pull/3409
Differential Revision: D6808264
Pulled By: maysamyabandeh
fbshipit-source-id: 0d7e2a054eb181e9a144fcb783cf0b2c77219bc0
Summary:
This is a pre-cleaning up before a major block based table iterator refactoring. BlockBasedTable::NewDataBlockIterator() will always return BlockIter. This simplifies the logic and code and enable further refactoring and optimization.
Closes https://github.com/facebook/rocksdb/pull/3398
Differential Revision: D6780165
Pulled By: siying
fbshipit-source-id: 273f7dc896724f682c0118fb69a359d9cc4418b4
Summary:
In DBIter, Prev() calls FindValueForCurrentKey() to search the current value backward. If it finds that there are too many stale value being skipped, it falls back to FindValueForCurrentKeyUsingSeek(), seeking directly to the key with snapshot sequence. After introducing read_callback, however, the key it seeks to might not be visible, according to read_callback. It thus needs to keep searching forward until the first visible value.
Closes https://github.com/facebook/rocksdb/pull/3382
Differential Revision: D6756148
Pulled By: yiwu-arbug
fbshipit-source-id: 064e39b1eec5e083af1c10142600f26d1d2697be
Summary:
To prevent user who implement the Iterator interface fail to implement SeekForPrev by mistake.
Closes https://github.com/facebook/rocksdb/pull/3402
Differential Revision: D6790681
Pulled By: yiwu-arbug
fbshipit-source-id: bd75b8ced30208982e0a1414d34384d93496827a
Summary:
In ColumnFamilySet destructor, assert it hold the last reference to cfd before destroy them.
Closes#3112
Closes https://github.com/facebook/rocksdb/pull/3397
Differential Revision: D6777967
Pulled By: yiwu-arbug
fbshipit-source-id: 60b19070e0c194b3b6146699140c1d68777866cb
Summary:
FIFO and Universal compaction options were recently made dynamic, but I forgot to update these comments. These would mislead anyone who is reading the code.
Closes https://github.com/facebook/rocksdb/pull/3399
Differential Revision: D6786358
Pulled By: sagar0
fbshipit-source-id: 57cfc412f63deaee29bbd82b863304821d60057d
Summary:
Now in leveled compaction, we allocate solely based on output target file size. If the total input size is smaller than the number, we should use the total input size instead. Also, cap the allocate size to 1GB.
Closes https://github.com/facebook/rocksdb/pull/3385
Differential Revision: D6762363
Pulled By: siying
fbshipit-source-id: e30906f6e9bff3ec847d2166e44cb49c92f98a13
Summary:
FreeBSD uses jemalloc as the base malloc implementation.
The patch has been functional on FreeBSD as of the MariaDB 10.2 port.
Closes https://github.com/facebook/rocksdb/pull/3386
Differential Revision: D6765742
Pulled By: yiwu-arbug
fbshipit-source-id: d55dbc082eecf640ef3df9a21f26064ebe6587e8
Summary:
When blob_files is empty, std::min_element will return blobfiles.end(), which cannot be dereference. Fixing it.
Closes https://github.com/facebook/rocksdb/pull/3387
Differential Revision: D6764927
Pulled By: yiwu-arbug
fbshipit-source-id: 86f78700132be95760d35ac63480dfd3a8bbe17a
Summary:
Flush() call could be waiting indefinitely if min_write_buffer_number_to_merge is used. Consider the sequence:
1. User call Flush() with flush_options.wait = true
2. The manual flush started in the background
3. New memtable become immutable because of writes. The new memtable will not trigger flush if min_write_buffer_number_to_merge is not reached.
4. The manual flush finish.
Because of the new memtable created at step 3 not being flush, previous logic of WaitForFlushMemTable() keep waiting, despite the memtables it intent to flush has been flushed.
Here instead of checking if there are any more memtables to flush, WaitForFlushMemTable() also check the id of the earliest memtable. If the id is larger than that of latest memtable at the time flush was initiated, it means all the memtable at the time of flush start has all been flush.
Closes https://github.com/facebook/rocksdb/pull/3378
Differential Revision: D6746789
Pulled By: yiwu-arbug
fbshipit-source-id: 35e698f71c7f90b06337a93e6825f4ea3b619bfa
Summary:
We have seen cases where it could be good to change TTL on already open DB.
Change ttl in TtlCompactionFilterFactory on open db.
Next time a filter is created, it will filter accroding to the set TTL.
Is this something that could be useful for others?
Any downsides?
Closes https://github.com/facebook/rocksdb/pull/3292
Differential Revision: D6731993
Pulled By: miasantreble
fbshipit-source-id: 73b94d69237b11e8730734389052429d621a6b1e
Summary:
When calling `DisableFileDeletions` followed by `GetSortedWalFiles`, we guarantee the files returned by the latter call won't be deleted until after file deletions are re-enabled. However, `GetSortedWalFiles` didn't omit files already planned for deletion via `PurgeObsoleteFiles`, so the guarantee could be broken.
We fix it by making `GetSortedWalFiles` wait for the number of pending purges to hit zero if file deletions are disabled. This condition is eventually met since `PurgeObsoleteFiles` is guaranteed to be called for the existing pending purges, and new purges cannot be scheduled while file deletions are disabled. Once the condition is met, `GetSortedWalFiles` simply returns the content of DB and archive directories, which nobody can delete (except for deletion scheduler, for which I plan to fix this bug later) until deletions are re-enabled.
Closes https://github.com/facebook/rocksdb/pull/3341
Differential Revision: D6681131
Pulled By: ajkr
fbshipit-source-id: 90b1e2f2362ea9ef715623841c0826611a817634
Summary:
After af92d4ad11, only exclusive manual compaction can have conflict. dc360df81e updated the conflict-checking test case accordingly. But we missed the point that exclusive manual compaction can only conflict with automatic compactions scheduled after it, since it waits on pending automatic compactions before it begins running.
This PR updates the test case to ensure the automatic compactions are scheduled after the manual compaction starts but before it finishes, thus ensuring a conflict. I also cleaned up the test case to use less space as I saw it cause out-of-space error on travis.
Closes https://github.com/facebook/rocksdb/pull/3375
Differential Revision: D6735162
Pulled By: ajkr
fbshipit-source-id: 020530a4e150a4786792dce7cec5d66b420cb884
Summary:
* Fix DBTest.CompactRangeWithEmptyBottomLevel lite build failure
* Fix DBTest.AutomaticConflictsWithManualCompaction failure introduce by #3366
* Fix BlockBasedTableTest::IndexUncompressed should be disabled if snappy is disabled
* Fix ASAN failure with DBBasicTest::DBClose test
Closes https://github.com/facebook/rocksdb/pull/3373
Differential Revision: D6732313
Pulled By: yiwu-arbug
fbshipit-source-id: 1eb9b9d9a8d795f56188fa9770db9353f6fdedc5
Summary:
Issue #3370 Simple fixes to make RocksDB project working also as a submodule of other bigger one.
Closes https://github.com/facebook/rocksdb/pull/3372
Differential Revision: D6729595
Pulled By: ajkr
fbshipit-source-id: eee2589e7a7c4322873dff8510eebd050301c54c
Summary:
If there's manual compaction in the queue, then "HaveManualCompaction(compaction_queue_.front())" will return true, and this cause too frequent MaybeScheduleFlushOrCompaction().
https://github.com/facebook/rocksdb/issues/3198
Closes https://github.com/facebook/rocksdb/pull/3366
Differential Revision: D6729575
Pulled By: ajkr
fbshipit-source-id: 96da04f8fd33297b1ccaec3badd9090403da29b0
Summary:
Currently, the only way to close an open DB is to destroy the DB
object. There is no way for the caller to know the status. In one
instance, the destructor encountered an error due to failure to
close a log file on HDFS. In order to prevent silent failures, we add
DB::Close() that calls CloseImpl() which must be implemented by its
descendants.
The main failure point in the destructor is closing the log file. This
patch also adds a Close() entry point to Logger in order to get status.
When DBOptions::info_log is allocated and owned by the DBImpl, it is
explicitly closed by DBImpl::CloseImpl().
Closes https://github.com/facebook/rocksdb/pull/3348
Differential Revision: D6698158
Pulled By: anand1976
fbshipit-source-id: 9468e2892553eb09c4c41b8723f590c0dbd8ab7d
Summary:
Java static builds are again broken, this time due Snappy version upgrade introduced in 90c1d81975 (#3331).
This is due to two reasons:
1. The new Snappy packages should now be downloaded from https://github.com/google/snappy/archive/<pkg.tar.gz> instead of https://github.com/google/snappy/releases/download/<pkg.tar.gz> which we are using now.
1. In addition to the the above URL change, Snappy changed its build from using autotools to CMake based : e69d9f8806/README.md (L65-L72)
So more changes are needed if we are going to upgrade to 1.1.7. Hence reverting the version upgrade until we figure them out.
Closes https://github.com/facebook/rocksdb/pull/3363
Differential Revision: D6716983
Pulled By: sagar0
fbshipit-source-id: f451a1bc5eb0bb090f4da07bc3e5ba72cf89aefa
Summary:
Split `JobContext::HaveSomethingToDelete` into two functions: itself and `JobContext::HaveSomethingToClean`. Now we won't call `DBImpl::PurgeObsoleteFiles` in cases where we really just need to call `JobContext::Clean`. The change is needed because I want to track pending calls to `PurgeObsoleteFiles` for a bug fix, which is much simpler if we only call it after `FindObsoleteFiles` finds files to delete.
Closes https://github.com/facebook/rocksdb/pull/3350
Differential Revision: D6690609
Pulled By: ajkr
fbshipit-source-id: 61502e7469288afe16a663a1b7df345baeaf246f
Summary:
This test often causes out-of-space error when run on travis. We don't want such stress tests in our unit test suite.
The bug in #596, which this test intends to expose, can be repro'd as long as the bottommost level(s) are empty when CompactRange is called. I rewrote the test to cover this simple case without writing a lot of data.
Closes https://github.com/facebook/rocksdb/pull/3362
Differential Revision: D6710417
Pulled By: ajkr
fbshipit-source-id: 9a1ec85e738c813ac2fee29f1d5302065ecb54c5
Summary:
Java build on PPC64le has been broken since a few months, due to #2716. Fixing it with the least amount of changes.
(We should cleanup a little around this code when time permits).
This should fix the build failures seen in http://140.211.168.68:8080/job/Rocksdb/ .
Closes https://github.com/facebook/rocksdb/pull/3359
Differential Revision: D6712938
Pulled By: sagar0
fbshipit-source-id: 3046e8f072180693de2af4762934ec1ace309ca4
Summary:
I installed the ruby dependencies and ran `bundle update nokogiri`. It depends on a newer version of "mini_portile2" which I missed in 9c2f64e148. Now `bundle install` works again.
Closes https://github.com/facebook/rocksdb/pull/3361
Differential Revision: D6710164
Pulled By: ajkr
fbshipit-source-id: 9a08d6cc6400ef495b715b3d68b04ce3f3367031
Summary:
Hello and thank you for RocksDB,
While looking into the buffered io used when an `OPTIONS` file is read I noticed the `OPTIONS` files produced by RocksDB 5.8.8 (and head of master) were just over 4096 bytes in size, resulting in the version of glibc I am using (glibc-2.17-196.el7) (on the filesystem used) being passed a 4K buffer for the `fread_unlocked` call and 2 system call reads using a 4096 buffer being used to read the contents of the `OPTIONS` file.
If the buffer size is increased to 8192 then 1 system call read is used to read the contents.
As I think the buffer size is just used for reading `OPTIONS` files, and I thought it likely that `OPTIONS` files have increased in size (as more options are added), I thought I would suggest an increase.
[ If the comments from the top of the `OPTIONS` file are removed, and white space from the start of lines is removed then the size can be reduced to be under 4K, but as more options are added the size seems likely to grow again. ]
Create a new database:
```
> ./ldb --create_if_missing --db=/tmp/rdb_tmp put 1 1
OK
```
The OPTIONS file is 4252 bytes:
```
> stat /tmp/rdb_tmp/OPTIONS* | head -n 2
File: ‘/tmp/rdb_tmp/OPTIONS-000005’
Size: 4252 Blocks: 16 IO Block: 4096 regular file
```
Before, the 4096 byte buffer is used from 2 system read calls:
```
> strace -f ./ldb --try_load_options --db=/tmp/rdb_tmp get DOES_NOT_EXIST 2>&1 |
grep -A 1 'RocksDB option file'
read(3, "# This is a RocksDB option file."..., 4096) = 4096
read(3, "e\n metadata_block_size=4096\n c"..., 4096) = 156
```
ltrace shows 4096 passed to fread_unlocked
```
> ltrace -S -f ./ldb --try_load_options --db=/tmp/rdb_tmp get DOES_NOT_EXIST 2>&1 |
grep -C 3 'RocksDB option file'
[pid 51013] fread_unlocked(0x7ffd5fbf2d50, 1, 4096, 0x7fd2e084e780 <unfinished ...>
[pid 51013] fstat@SYS(3, 0x7ffd5fbf28f0) = 0
[pid 51013] mmap@SYS(nil, 4096, 3, 34, -1, 0) = 0x7fd2e318c000
[pid 51013] read@SYS(3, "# This is a RocksDB option file."..., 4096) = 4096
[pid 51013] <... fread_unlocked resumed> ) = 4096
...
```
After, the 8192 byte buffer is used from 1 system read call:
```
> strace -f ./ldb --try_load_options --db=/tmp/rdb_tmp get DOES_NOT_EXIST 2>&1 | grep -A 1 'RocksDB option file'
read(3, "# This is a RocksDB option file."..., 8192) = 4252
read(3, "", 4096) = 0
```
ltrace shows 8192 passed to fread_unlocked
```
> ltrace -S -f ./ldb --try_load_options --db=/tmp/rdb_tmp get DOES_NOT_EXIST 2>&1 | grep -C 3 'RocksDB option file'
[pid 146611] fread_unlocked(0x7ffcfba382f0, 1, 8192, 0x7fc4e844e780 <unfinished ...>
[pid 146611] fstat@SYS(3, 0x7ffcfba380f0) = 0
[pid 146611] mmap@SYS(nil, 4096, 3, 34, -1, 0) = 0x7fc4eaee0000
[pid 146611] read@SYS(3, "# This is a RocksDB option file."..., 8192) = 4252
[pid 146611] read@SYS(3, "", 4096) = 0
[pid 146611] <... fread_unlocked resumed> ) = 4252
[pid 146611] feof(0x7fc4e844e780) = 1
```
Closes https://github.com/facebook/rocksdb/pull/3294
Differential Revision: D6653684
Pulled By: ajkr
fbshipit-source-id: 222f25f5442fefe1dcec18c700bd9e235bb63491
Summary:
to save a string copy for some use cases.
The change is pretty straightforward, please feel free to let me know if you want to suggest any tests for it.
Closes https://github.com/facebook/rocksdb/pull/3349
Differential Revision: D6706828
Pulled By: yiwu-arbug
fbshipit-source-id: 873ce4442937bdc030b395c7f99228eda7f59eb7
Summary:
Re-use metadata for reading Compression Dictionary on BlockBased
table open, this saves two reads from disk.
This helps to our 999 percentile in 5.6.1 where prefetch buffer is not present.
Closes https://github.com/facebook/rocksdb/pull/3354
Differential Revision: D6695753
Pulled By: ajkr
fbshipit-source-id: bb8acd9e9e66e65b89c548ab8940570ae360333c
Summary:
It was using the same directory as `db_options_test` so transiently failed when unit tests were run in parallel.
Closes https://github.com/facebook/rocksdb/pull/3352
Differential Revision: D6691649
Pulled By: ajkr
fbshipit-source-id: bee433484fec4faedd5cadf2db3c92fdcc99a170
Summary:
- Change directory name from "db_test" to "checkpoint_test". Previously it used the same directory as `db_test`
- Systematically cleanup snapshot and snapshot staging directories before each test. Previously a failed test run caused subsequent runs to fail, particularly when the first failure caused "snapshot.tmp" to not be cleaned up.
Closes https://github.com/facebook/rocksdb/pull/3351
Differential Revision: D6691015
Pulled By: ajkr
fbshipit-source-id: 4fc2ac2e21ff2617ea0e96297c5132b5f2eefd79
Summary:
Most popular versions of GCC can't identify platform on ARM if "-march=native" is specified. Remove it to unblock most people.
Closes https://github.com/facebook/rocksdb/pull/3346
Differential Revision: D6690544
Pulled By: siying
fbshipit-source-id: bbaba9fe2645b6b37144b36ea75beeff88992b49
Summary:
I experienced weird segfault because of this mismatch of type in log formatting. Fix it.
Closes https://github.com/facebook/rocksdb/pull/3345
Differential Revision: D6687224
Pulled By: siying
fbshipit-source-id: c51fb1c008b7ebc3efdc353a4adad3e8f5b3e9de
Summary:
got confused while reading `FindObsoleteFiles` due to thinking it's a local variable, so renamed it properly
Closes https://github.com/facebook/rocksdb/pull/3342
Differential Revision: D6684797
Pulled By: ajkr
fbshipit-source-id: a4df0aae1cccce99d4dd4d164aadc85b17707132
Summary:
The macro was added by mistake in #2372
Closes https://github.com/facebook/rocksdb/pull/3343
Differential Revision: D6681356
Pulled By: yiwu-arbug
fbshipit-source-id: 4180172fb0eaef4189c07f219241e0c261c03461
Summary:
This patch addresses a couple of minor TODOs for WritePrepared Txn such as double checking some assert statements at runtime as well, skip extra AddPrepared in non-2pc transactions, and safety check for infinite loops.
Closes https://github.com/facebook/rocksdb/pull/3302
Differential Revision: D6617002
Pulled By: maysamyabandeh
fbshipit-source-id: ef6673c139cb49f64c0879508d2f573b78609aca
Andrew Kryczka