How sure are you that the open file count never goes beyond 50K? Are those
numbers just from a snapshot after it crashed? It's possible rocks is
creating a large number of files just for a short period of time (maybe
while compacting) that causes the open file count to spike and go back down.
For things to try, you should set the rocks config max.open.files to
something less than infinity...if you're OS limit is 1 million and you have
(rounding up) ~5k rocks instances, set this to 1 million / 5k = 200. If you
set a lower limit and still hit this error, we can go from there
On Tue, Jul 2, 2019 at 11:10 PM emailtokir...@gmail.com <
emailtokir...@gmail.com> wrote:
>
>
> On 2019/07/03 05:46:45, Sophie Blee-Goldman <sop...@confluent.io> wrote:
> > It sounds like rocksdb *is* honoring your configs -- the max.open.files
> > config is an internal restriction that tells rocksdb how many open files
> it
> > is allowed to have, so if that's set to -1 (infinite) it won't ever try
> to
> > limit its open files and you may hit the OS limit.
> >
> > Think of it this way: if you have 100 rocksdb instances and a OS limit of
> > 500, you should set max.open.files to 5 to avoid hitting this limit
> > (assuming there are no other open files on the system, in reality you'd
> > want some extra room there)
> >
> > On Tue, Jul 2, 2019 at 7:53 PM emailtokir...@gmail.com <
> > emailtokir...@gmail.com> wrote:
> >
> > >
> > >
> > > On 2019/06/28 23:29:16, John Roesler <j...@confluent.io> wrote:
> > > > Hey all,
> > > >
> > > > If you want to figure it out theoretically, if you print out the
> > > > topology description, you'll have some number of state stores listed
> > > > in there. The number of Rocks instances should just be
> > > > (#global_state_stores +
> > > > sum(#partitions_of_topic_per_local_state_store)) . The number of
> > > > stream threads isn't relevant here.
> > > >
> > > > You can also figure it out empirically: the first level of
> > > > subdirectories in the state dir are Tasks, and then within that, the
> > > > next level is Stores. You should see the store directory names match
> > > > up with the stores listed in the topology description. The number of
> > > > Store directories is exactly the number of RocksDB instances you
> have.
> > > >
> > > > There are also metrics corresponding to each of the state stores, so
> > > > you can compute it from what you find in the metrics.
> > > >
> > > > Hope that helps,
> > > > -john
> > > >
> > > > On Thu, Jun 27, 2019 at 6:46 AM Patrik Kleindl <pklei...@gmail.com>
> > > wrote:
> > > > >
> > > > > Hi Kiran
> > > > > Without much research my guess would be "num_stream_threads *
> > > > > (#global_state_stores +
> > > sum(#partitions_of_topic_per_local_state_store))"
> > > > > So 10 stores (regardless if explicitly defined or implicitely
> because
> > > of
> > > > > some stateful operation) with 10 partitions each should result in
> 100
> > > > > Rocksdb instances if you are running at the default of
> > > num_stream_threads=1.
> > > > >
> > > > > As I wrote before, start with 100.
> > > > > If the error persists, half the number, if not, double it ;-)
> Repeat as
> > > > > needed.
> > > > >
> > > > > If you reach the single-digit-range and the error still shows up,
> start
> > > > > searching for any iterators over a store you might not have closed.
> > > > >
> > > > > br, Patrik
> > > > >
> > > > > On Thu, 27 Jun 2019 at 13:11, emailtokir...@gmail.com <
> > > > > emailtokir...@gmail.com> wrote:
> > > > >
> > > > > >
> > > > > >
> > > > > > On 2019/06/27 09:02:39, Patrik Kleindl <pklei...@gmail.com>
> wrote:
> > > > > > > Hello Kiran
> > > > > > >
> > > > > > > First, the value for maxOpenFiles is per RocksDB instance, and
> the
> > > number
> > > > > > > of those can get high if you have a lot of topic partitions
> etc.
> > > > > > > Check the directory (state dir) to see how many there are.
> > > > > > > Start with a low value (100) and see if that has some effect.
> > > > > > >
> > > > > > > Second, because I just found out, you should use
> > > > > > > BlockBasedTableConfig tableConfig = (BlockBasedTableConfig)
> > > > > > > options.tableFormatConfig();
> > > > > > > tableConfig.setBlockCacheSize(100*1024*1024L);
> > > > > > > tableConfig.setBlockSize(8*1024L);
> > > > > > > instead of creating a new object to prevent accidently messing
> up
> > > > > > > references.
> > > > > > >
> > > > > > > Hope that helps
> > > > > > > best regards
> > > > > > > Patrik
> > > > > > >
> > > > > > > On Thu, 27 Jun 2019 at 10:46, emailtokir...@gmail.com <
> > > > > > > emailtokir...@gmail.com> wrote:
> > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > On 2019/06/26 21:58:02, Patrik Kleindl <pklei...@gmail.com>
> > > wrote:
> > > > > > > > > Hi Kiran
> > > > > > > > > You can use the RocksDBConfigSetter and pass
> > > > > > > > >
> > > > > > > > > options.setMaxOpenFiles(100);
> > > > > > > > >
> > > > > > > > > to all RocksDBs for the Streams application which limits
> how
> > > many are
> > > > > > > > > kept open at the same time.
> > > > > > > > >
> > > > > > > > > best regards
> > > > > > > > >
> > > > > > > > > Patrik
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > On Wed, 26 Jun 2019 at 16:14, emailtokir...@gmail.com <
> > > > > > > > > emailtokir...@gmail.com> wrote:
> > > > > > > > >
> > > > > > > > > > Hi,
> > > > > > > > > >
> > > > > > > > > > We are using Kafka streams DSL APIs for doing some
> counter
> > > > > > aggregations
> > > > > > > > > > (running on OpenJDK 11.0.2). Our topology has some 400
> sub
> > > > > > topologies
> > > > > > > > & we
> > > > > > > > > > are using 8 partitions in source topic. When we start
> > > pumping more
> > > > > > > > load, we
> > > > > > > > > > start getting RockDBException stating "too many open
> files".
> > > > > > > > > >
> > > > > > > > > > Here are the stack trace samples:
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> ------------------------------------------------------------------------------------------
> > > > > > > > > > Caused by: org.rocksdb.RocksDBException: while open a
> file
> > > for
> > > > > > lock:
> > > > > > > > > > PPPPPPPPPPP.1512000000/LOCK: Too many open files
> > > > > > > > > > at org.rocksdb.RocksDB.open(Native Method)
> > > > > > > > > > at org.rocksdb.RocksDB.open(RocksDB.java:235)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.RocksDBStore.openDB(RocksDBStore.java:156)
> > > > > > > > > > ... 24 common frames omitted
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > Caused by:
> > > org.apache.kafka.streams.errors.ProcessorStateException:
> > > > > > > > Error
> > > > > > > > > > while executing flush from store XXXXXXXXXXX.1512000000
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.RocksDBStore.flushInternal(RocksDBStore.java:397)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.RocksDBStore.flush(RocksDBStore.java:388)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.Segments.flush(Segments.java:163)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.RocksDBSegmentedBytesStore.flush(RocksDBSegmentedBytesStore.java:178)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.WrappedStateStore$AbstractStateStore.flush(WrappedStateStore.java:85)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.WrappedStateStore$AbstractStateStore.flush(WrappedStateStore.java:85)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.CachingWindowStore.flush(CachingWindowStore.java:130)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.MeteredWindowStore.flush(MeteredWindowStore.java:177)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.processor.internals.ProcessorStateManager.flush(ProcessorStateManager.java:217)
> > > > > > > > > > ... 10 more
> > > > > > > > > > Caused by: org.rocksdb.RocksDBException: While open a
> file
> > > for
> > > > > > > > appending:
> > > > > > > > > > YYYYYYYYYYYYY.1512000000/000007.dbtmp: Too many open
> files
> > > > > > > > > > at org.rocksdb.RocksDB.flush(Native Method)
> > > > > > > > > > at org.rocksdb.RocksDB.flush(RocksDB.java:3401)
> > > > > > > > > > at org.rocksdb.RocksDB.flush(RocksDB.java:3361)
> > > > > > > > > > at
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> org.apache.kafka.streams.state.internals.RocksDBStore.flushInternal(RocksDBStore.java:395)
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > >
> ------------------------------------------------------------------------------------------
> > > > > > > > > >
> > > > > > > > > > We tried increasing the open files limit at OS level to
> some
> > > decent
> > > > > > > > > > number.. but still no luck. Obviously we don't want to
> have
> > > > > > boundless
> > > > > > > > open
> > > > > > > > > > files..
> > > > > > > > > >
> > > > > > > > > > We also tried to play with commit interval(
> > > > > > kafka.commit.interval.ms)
> > > > > > > > and
> > > > > > > > > > cache size (kafka.cache.max.bytes.buffering) .. but no
> luck
> > > there
> > > > > > > > either.
> > > > > > > > > >
> > > > > > > > > > KAFKA-3904 talks about it.. but it was resolved long
> back..
> > > > > > > > > >
> > > > > > > > > > Any other config tuning we have to do?
> > > > > > > > > >
> > > > > > > > > > Appreciate any help in this regard!
> > > > > > > > > >
> > > > > > > > > > Thanks,
> > > > > > > > > > Kiran
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > > > Hi Patrik/All,
> > > > > > > >
> > > > > > > > Thanks for providing some valuable pointer!
> > > > > > > >
> > > > > > > > I did that & it doesn't seems to work.
> > > > > > > >
> > > > > > > > Here is how my custom config setter looks like:
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > >
> > >
> ----------------------------------------------------------------------------------------------------
> > > > > > > >
> > > > > > > >
> > > > > > > > @Override
> > > > > > > > public void setConfig(final String storeName, final
> > > Options
> > > > > > > > options, final Map<String, Object> configs) {
> > > > > > > > // See #1 below.
> > > > > > > > BlockBasedTableConfig tableConfig = new
> > > > > > > > org.rocksdb.BlockBasedTableConfig();
> > > > > > > >
> > > > > > > > tableConfig.setBlockCacheSize(16 * 1024 * 1024L);
> > > > > > > > // See #2 below.
> > > > > > > > tableConfig.setBlockSize(16 * 1024L);
> > > > > > > > // See #3 below.
> > > > > > > > tableConfig.setCacheIndexAndFilterBlocks(false);
> > > > > > > > //
> > > tableConfig.setPinL0FilterAndIndexBlocksInCache(true);
> > > > > > > > options.setMaxOpenFiles(-1);
> > > > > > > > options.setTableFormatConfig(tableConfig);
> > > > > > > > // See #4 below.
> > > > > > > > options.setMaxWriteBufferNumber(2);
> > > > > > > > }
> > > > > > > >
> > > > > > > >
> > > > > >
> > >
> ----------------------------------------------------------------------------------------------------
> > > > > > > > I tried many options with this:
> > > > > > > > 1. tableConfig.setCacheIndexAndFilterBlocks(true); ----> as
> per
> > > docs (
> > > > > > > >
> > > > > >
> > >
> https://github.com/facebook/rocksdb/wiki/Memory-usage-in-RocksDB#indexes-and-filter-blocks
> > > > > > )
> > > > > > > > if we set to true, the max_open_files shouldn't play a role.
> But
> > > I was
> > > > > > > > still getting too many open files exception from Rocksdb
> > > > > > > >
> > > > > > > > 2. tableConfig.setCacheIndexAndFilterBlocks(true);
> > > > > > > > tableConfig.setPinL0FilterAndIndexBlocksInCache(true); ---->
> no
> > > luck;
> > > > > > same
> > > > > > > > exception
> > > > > > > >
> > > > > > > > 3. tableConfig.setCacheIndexAndFilterBlocks(false); and
> > > > > > > > options.setMaxOpenFiles(50000); -----> This also
> resulted
> > > with
> > > > > > same
> > > > > > > > exception.. with java process having ~24K open files
> > > > > > > >
> > > > > > > > 4. tableConfig.setCacheIndexAndFilterBlocks(false); and
> > > > > > > > options.setMaxOpenFiles(-1); -----> This also resulted
> with
> > > same
> > > > > > > > exception.. with java process having ~24K ope files. As per
> the
> > > doc,
> > > > > > if we
> > > > > > > > set to -1, it means infinite and controlled by underlying OS
> > > limit.
> > > > > > > >
> > > > > > > > I am using MacOS Mojave (10.14.4) and OpenJDK 11.0.2. At OS
> > > level, I
> > > > > > have
> > > > > > > > bumped the open files limit to 1 million.
> > > > > > > >
> > > > > > > > $ ulimit -a
> > > > > > > > core file size (blocks, -c) 0
> > > > > > > > data seg size (kbytes, -d) unlimited
> > > > > > > > file size (blocks, -f) unlimited
> > > > > > > > max locked memory (kbytes, -l) unlimited
> > > > > > > > max memory size (kbytes, -m) unlimited
> > > > > > > > open files (-n) 1000000
> > > > > > > > pipe size (512 bytes, -p) 1
> > > > > > > > stack size (kbytes, -s) 8192
> > > > > > > > cpu time (seconds, -t) unlimited
> > > > > > > > max user processes (-u) 1418
> > > > > > > > virtual memory (kbytes, -v) unlimited
> > > > > > > >
> > > > > > > >
> > > > > > > > Am I missing some other config here?
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Kiran
> > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > > > Hi Patrik,
> > > > > >
> > > > > > Thanks for quick response!
> > > > > >
> > > > > > I just checked the state dir. It has total of 3152 sub folders
> and
> > > total
> > > > > > of 15451 files (within sub folders..).
> > > > > >
> > > > > > With this what should be the number that I should use?
> > > > > >
> > > > > > How many instances of rocksdb will be used? Any formula to
> determine
> > > that?
> > > > > >
> > > > > > Thanks again,
> > > > > > Kiran
> > > > > >
> > > >
> > >
> > > Hi John/Patrik,
> > >
> > > Thanks for sharing some more insights!
> > >
> > > So we have ~3.2K state store directories (which means those many
> rocksdb
> > > instances.
> > >
> > > So when we tried with these config params:
> > > ------------------
> > > cache.index.and.filter.blocks=false
> > > max.open.files=-1
> > > block.cache.size=100* 1024 * 1024L
> > > block.size=8*1024L
> > > max.write.buffer.number=2
> > > ------------------
> > > We still got too many open files exception from rocksdb side. At that
> time
> > > the total open files on the VM were ~46K. At OS level we have
> increased the
> > > max open files limit to 1 million.
> > >
> > > As per above config, "max.open.files=-1" it means infinite open files
> for
> > > rocksdb and it's controlled by OS open file limit (which is 1 million
> in
> > > our case). We are not able to understand why rocksdb is not honouring
> our
> > > config params?
> > >
> > > P.S: we will not go with "max.open.files=-1" in production.. we are
> just
> > > trying to understand how to overcome this exception by trying various
> > > combinations of config params.
> > >
> > > Are we missing some other key rocksdb configs here?
> > >
> > > Thanks,
> > > Kiran
> > >
> > >
> > >
> >
> Hi Sophie,
>
> If it's honouring the config params, then why it should give too many open
> files exception when we have set 1 million at OS level? When we check the
> open files count, we hardly see them at ~42K.. and it never goes beyond
> 50K. Why is it so? are there any other config params which we have to tune?
>
> Thanks,
> Kiran
>
