Hi, penghui
> The new API does not necessarily have to query by topic one by one,
we have listed all the "topic -> position" of a bundle?
I see. After we got all the positions of the topics we want to split in a
bundle, it's quite easy for us to decide how to it.
Haiting Jiang <jianghait...@apache.org> 于2022年2月20日周日 12:05写道：
> > Do you have an example for affinity? I don't fully understand how this is
> > used
> > in practice.
>
> IMO, this affinity serves the purpose of isolating an abnormal topic to
> some spare
> brokers. These brokers host these kind of topics only. Here are some
> cases :
>
> 1. A topic may have unexpected short spike traffic flows periodically and
> causing broker overloads and negative impact on other topics.
> Until we have more proper solutions, we can always isolate these topics
> first,
> and make the service recover time as small as possible.
>
> 2. Some users may encounter some bugs in brokers, and we can isolate the
> topic to
> exclusive brokers, and use more radical approach to locate the bug, like
> enable debug
> level logs or even add some temporary code patch.
>
> 3. User may already have configured failure domain and anti-affinity
> namespace, but with
> business logic code changes, some topic may need to migrate from one
> namespace
> to another. This will take some time for user to change the client side
> config.
> In the meanwhile, we can isolate the topic first.
>
> Thanks,
> Haiting
>
> On 2022/02/18 15:26:09 PengHui Li wrote:
> > Hi Haiting,
> >
> > > I think this approach have more potential with abnormal topic
> isolation.
> > If we can introduce
> > some kind of bundle isolation strategy, (like broker-bundle affinity and
> > anti-affinity mechanism), we can easily isolate some unexpected traffic
> to
> > some empty brokers.
> > IMO, this would improve the stability of broker cluster.
> >
> > if I understand correctly, it looks like if we have a partitioned topic
> > with 10
> > partitions under a namespace with 16 bundles, if applies the
> anti-affinity
> > policy,
> > partition-0 map to bundle 0, partition-1 map to bundle 1, and so on.
> > Of course, it is not necessary for every partitioned topic to start from
> > bundle 0,
> > we can use the partition-0 hash to determine the start bundle index.
> >
> > Do you have an example for affinity? I don't fully understand how this is
> > used
> > in practice.
> >
> > Best,
> > Penghui
> >
> > On Fri, Feb 18, 2022 at 11:16 PM PengHui Li <peng...@apache.org> wrote:
> >
> > > Hi Aloys,
> > >
> > > > Do you mean that
> > > 1. First, add a new API, maybe `getHashPositioin`, to get the hash
> > > position in a bundle
> > > 2. Then use this position to split the overloaded bundle
> > > If so, when we split a bundle with multi partitions of a topic, we
> need to
> > > call the `getHashPositioin` multi times to get the middle position of
> all
> > > these positions.
> > >
> > > Yes, this want I mean. In this way, users can control to assign 1
> topic or
> > > 3 topics to one bundle. This is more like increasing the transparency
> of
> > > the topic in the bundle, you can all the positions of the topics, so
> how
> > > planning for bundle splitting becomes more flexible.
> > >
> > > The new API does not necessarily have to query by topic one by one,
> > > we have listed all the "topic -> position" of a bundle?
> > >
> > > Thanks,
> > > Penghui
> > >
> > > On Fri, Feb 18, 2022 at 4:51 PM Haiting Jiang <jianghait...@apache.org
> >
> > > wrote:
> > >
> > >> Hi Aloys,
> > >> +1 for this great PIP.
> > >>
> > >> > The Admin CLI `bin/pulsar-admin namespaces split-bundle -b
> > >> ${bundle_range}`
> > >> > will add a new parameter "--topic" or "-t" for `outstanding topic`
> > >> name.
> > >>
> > >> Do we have limitation on this "topic" parameter. Can this be a
> > >> partitioned topic?
> > >> If so, will this new algorithm split the bundle into more than 2
> bundles?
> > >> like each bundle for
> > >> one partition.
> > >>
> > >> > This algorithm has a disadvantage, it can only deal
> > >> > with one `outstanding topic`.
> > >>
> > >> For this disadvantage, I think it can be solved by extends the "topic"
> > >> parameter from one topic to a topic list.
> > >>
> > >> > The other algorithm is to split the bundle at the hashcode point of
> the
> > >> > `outstanding partition` which will split the bundle into three
> bundles
> > >> once
> > >> > a time. The middle one contains the only point the hashcode of the
> > >> > `outstanding partition, the left one is less than the hashcode, the
> > >> right
> > >> > one is more than the hashcode.
> > >> > E.g. if we have a bundle 0x00_0x10 contains two `outstanding
> partition`
> > >> > (partition-x and partition-y) whose hashcode is 0x03 and 0x07, this
> > >> > algorithm is going to split bundle the bundle into five new
> bundles,
> > >> > 0x00_0x03, 0x03_0x04( for parition-x), 0x04_0x07, 0x07_0x08( for
> > >> > partition-y), 0x08_0x10.
> > >>
> > >> I think this approach have more potential with abnormal topic
> isolation.
> > >> If we can introduce
> > >> some kind of bundle isolation strategy, (like broker-bundle affinity
> and
> > >> anti-affinity mechanism), we can easily isolate some unexpected
> traffic to
> > >> some empty brokers.
> > >> IMO, this would improve the stability of broker cluster.
> > >>
> > >> Thanks,
> > >> Haiting
> > >>
> > >> On 2022/02/17 15:47:15 Aloys Zhang wrote:
> > >> > Hi Pulsar Community,
> > >> >
> > >> > This is a PIP discussion on how to support split partitions
> belonging to
> > >> > specified topics in a bundle.
> > >> >
> > >> > The issue can be found:
> https://github.com/apache/pulsar/issues/13761
> > >> >
> > >> > I copy the content here for convenience, any suggestions are
> welcome and
> > >> > appreciated.
> > >> >
> > >> >
> > >> > ## Motivation
> > >> >
> > >> > As we all know, a namespace bundle may contain lots of partitions
> > >> belonging
> > >> > to different topics.
> > >> > The throughput of these topics may vary greatly. Some topics may
> with
> > >> very
> > >> > high rate/throughput while other topics have a very low
> rate/throughput.
> > >> >
> > >> > These partitions with high rate/throughput can cause broker
> overload and
> > >> > bundle unloading.
> > >> > At this point, if we split bundle manually with
> `range_equally_divide`
> > >> or
> > >> > `topic_count_equally_divide` split algorithm, there may need many
> times
> > >> > split before these high rate/through partitions assigned to
> different
> > >> new
> > >> > bundles.
> > >> >
> > >> > For convenience, we call these high throughput topics `outstanding
> > >> topic`
> > >> > and their partitions `outstanding partition` in this PIP.
> > >> >
> > >> > ## Goal
> > >> >
> > >> > Our goal is to make it easier to split `outstanding partition` into
> new
> > >> > bundles.
> > >> >
> > >> > There are two alternative ways to achieve this. Either of them will
> add
> > >> a
> > >> > new algorithm for bundle split. The difference is how the new bundle
> > >> split
> > >> > algorithm is implemented.
> > >> >
> > >> > One algorithm is to split bundle by `outstanding topic` which will
> split
> > >> > the bundle into two new bundles and each new bundle contains an
> equally
> > >> > `outstanding partition` once a time.
> > >> > E.g, a bundle contains lots of topic partitions, and only one
> > >> `outstanding
> > >> > topic`(T) with 2 `outstanding partition` (T-partition-n,
> > >> Tpartition-n+1).
> > >> > This algorithm split this bundle at the middle point of these two
> > >> > partition's hashcode. This algorithm has a disadvantage, it can
> only
> > >> deal
> > >> > with one `outstanding topic`.
> > >> >
> > >> > So we raised up another algorithm.
> > >> >
> > >> > The other algorithm is to split the bundle at the hashcode point of
> the
> > >> > `outstanding partition` which will split the bundle into three
> bundles
> > >> once
> > >> > a time. The middle one contains the only point the hashcode of the
> > >> > `outstanding partition, the left one is less than the hashcode, the
> > >> right
> > >> > one is more than the hashcode.
> > >> > E.g. if we have a bundle 0x00_0x10 contains two `outstanding
> partition`
> > >> > (partition-x and partition-y) whose hashcode is 0x03 and 0x07, this
> > >> > algorithm is going to split bundle the bundle into five new
> bundles,
> > >> > 0x00_0x03, 0x03_0x04( for parition-x), 0x04_0x07, 0x07_0x08( for
> > >> > partition-y), 0x08_0x10.
> > >> >
> > >> > ## API Changes
> > >> >
> > >> > The Admin CLI `bin/pulsar-admin namespaces split-bundle -b
> > >> ${bundle_range}`
> > >> > will add a new parameter "--topic" or "-t" for `outstanding topic`
> > >> name.
> > >> >
> > >> > The split interface changed from
> > >> >
> > >> > ```JAVA
> > >> > void splitNamespaceBundle(String namespace, String bundle, boolean
> > >> > unloadSplitBundles, String splitAlgorithmName)throws
> > >> PulsarAdminException;
> > >> > ```
> > >> >
> > >> > to
> > >> >
> > >> > ```java
> > >> > void splitNamespaceBundle(String namespace, String bundle, boolean
> > >> > unloadSplitBundles,
> > >> > String splitAlgorithmName, String
> topic)
> > >> > throws PulsarAdminException;
> > >> > ```
> > >> >
> > >> > ## Implementation
> > >> >
> > >> > There are changes both from the Admin CLI and the broker side.
> > >> >
> > >> > First, Admin CLI for split bundle should support to specify the
> > >> > `outstanding topic`,
> > >> >
> > >> > ```java
> > >> > /**
> > >> > * Split namespace bundle.
> > >> > *
> > >> > * @param namespace
> > >> > * @param bundle range of bundle to split
> > >> > * @param unloadSplitBundles
> > >> > * @param splitAlgorithmName
> > >> > * @param topic
> > >> > * @throws PulsarAdminException
> > >> > */
> > >> > void splitNamespaceBundle(String namespace, String bundle,
> boolean
> > >> > unloadSplitBundles,
> > >> > String splitAlgorithmName, String
> topic)
> > >> > throws PulsarAdminException;
> > >> >
> > >> > ```
> > >> >
> > >> > ```java
> > >> > /**
> > >> > * Split namespace bundle asynchronously.
> > >> > *
> > >> > * @param namespace
> > >> > * @param bundle range of bundle to split
> > >> > * @param unloadSplitBundles
> > >> > * @param splitAlgorithmName
> > >> > */
> > >> > CompletableFuture<Void> splitNamespaceBundleAsync(
> > >> > String namespace, String bundle, boolean
> unloadSplitBundles,
> > >> > String splitAlgorithmName, String topic);
> > >> > ```
> > >> >
> > >> > And for the broker side, first encapsulates the parameters for
> bundle
> > >> split
> > >> > into a new class `BundleSplitOption`
> > >> >
> > >> > ```java
> > >> > public class BundleSplitOption {
> > >> > private NamespaceService service;
> > >> > private NamespaceBundle bundle;
> > >> > private String topic;
> > >> > }
> > >> > ```
> > >> >
> > >> > add a new split algorithm
> > >> >
> > >> > ```java
> > >> > ublic class SpecifiedTopicCountEquallyDivideBundleSplitAlgorithm
> > >> implements
> > >> > NamespaceBundleSplitAlgorithm {
> > >> > @Override
> > >> > public CompletableFuture<List<Long>>
> > >> getSplitBoundary(BundleSplitOption
> > >> > bundleSplitOption) {
> > >> >
> > >> > });
> > >> > }
> > >> > }
> > >> > ```
> > >> >
> > >> > add the new algorithm to `NamespaceBundleSplitAlgorithm`
> > >> >
> > >> > ```JAVA
> > >> > String SPECIFIED_TOPIC_COUNT_EQUALLY_DIVIDE =
> > >> > "specified_topic_count_equally_divide";
> > >> >
> > >> > List<String> AVAILABLE_ALGORITHMS =
> > >> > Lists.newArrayList(RANGE_EQUALLY_DIVIDE_NAME,
> > >> > TOPIC_COUNT_EQUALLY_DIVIDE,
> > >> > SPECIFIED_TOPIC_COUNT_EQUALLY_DIVIDE);
> > >> >
> > >> > NamespaceBundleSplitAlgorithm
> > >> SPECIFIED_TOPIC_COUNT_EQUALLY_DIVIDE_ALGO =
> > >> > new
> SpecifiedTopicCountEquallyDivideBundleSplitAlgorithm();
> > >> > ```
> > >> >
> > >> > modify the `splitAndOwnBundle` and `splitAndOwnBundleOnceAndRetry`
> for
> > >> > [[NamespaceService.java](
> > >> >
> > >>
> https://github.com/apache/pulsar/pull/13796/files#diff-99867fd2e328e0a689daa8f60d174aa96d87dd0d0fd29b9e68fe2e1f377b55a1)](https://github.com/apache/pulsar/pull/13796/files#diff-99867fd2e328e0a689daa8f60d174aa96d87dd0d0fd29b9e68fe2e1f377b55a1
> > >> )
> > >> >
> > >> >
> > >> > ```java
> > >> > public CompletableFuture<Void> splitAndOwnBundle(NamespaceBundle
> bundle,
> > >> > boolean unload,
> > >> >
> > >> > NamespaceBundleSplitAlgorithm splitAlgorithm, String topic) {
> > >> >
> > >> > final CompletableFuture<Void> unloadFuture = new
> > >> > CompletableFuture<>();
> > >> > final AtomicInteger counter = new
> > >> > AtomicInteger(BUNDLE_SPLIT_RETRY_LIMIT);
> > >> > splitAndOwnBundleOnceAndRetry(bundle, unload, counter,
> > >> > unloadFuture, splitAlgorithm, topic);
> > >> >
> > >> > return unloadFuture;
> > >> > }
> > >> > ```
> > >> >
> > >> > ```java
> > >> > void splitAndOwnBundleOnceAndRetry(NamespaceBundle bundle,
> > >> > boolean unload,
> > >> > AtomicInteger counter,
> > >> > CompletableFuture<Void>
> > >> > completionFuture,
> > >> > NamespaceBundleSplitAlgorithm
> > >> > splitAlgorithm,
> > >> > String topic) {
> > >> > ```
> > >> >
> > >> > Also, we change the REST api and broker.conf
> > >> >
> > >> > ```java
> > >> > public void splitNamespaceBundle(
> > >> > @Suspended final AsyncResponse asyncResponse,
> > >> > @PathParam("property") String property,
> > >> > @PathParam("cluster") String cluster,
> > >> > @PathParam("namespace") String namespace,
> > >> > @PathParam("bundle") String bundleRange,
> > >> > @QueryParam("authoritative") @DefaultValue("false")
> boolean
> > >> > authoritative,
> > >> > @QueryParam("unload") @DefaultValue("false") boolean
> unload,
> > >> > @QueryParam("topic") @DefaultValue("") String topic) {}
> > >> > ```
> > >> >
> > >> > ```shell
> > >> >
> > >>
> supportedNamespaceBundleSplitAlgorithms=range_equally_divide,topic_count_equally_divide,specified_topic_count_equally_divide
> > >> > ```
> > >> >
> > >>
> > >
> >
>
