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Posted to user@helix.apache.org by Hang Qi <ha...@gmail.com> on 2015/10/23 19:06:43 UTC

Question about HelixPropertyStore

Hi All,

We are using HelixPropertyStore in helix 0.6.4. The doc says "Helix
supports caching the data with a write-through cache", so if I have two
nodes A and B, if A made changes on some property in PropertyStore after B,
will B get latest one?  In our test, we kind of observe that B will still
use its cached version, is that expected, do we have a way to get latest
version on B?

Besides, we notice following log, looks like we need to specify paths for
watchers, but we do not find a way how to do that in HelixPropertyStore.

WARN  org.apache.helix.manager.zk.ZkCacheBaseDataAccessor  - ZkCachePaths
is null or empty. Will not start ZkCacheEventThread

Moreover, do we support concurrent set on HelixPropertyStore? Just saw
following description on AutoFallbackPropertyStore: "Property store that
does auto fallback to an old location. Assuming no concurrent updates"

Any suggestions ?

Thanks
Hang Qi

Re: Question about HelixPropertyStore

Posted by Hang Qi <ha...@gmail.com>.
Hi Kishore,

Thanks for providing the info, I will take a look.

Previously I am using HelixManager#getHelixPropertyStore to get
HelixPropertyStore.

Thanks
Hang Qi

On Fri, Oct 23, 2015 at 4:13 PM, kishore g <g....@gmail.com> wrote:

> Hi Hang,
>
> This api is a bit confusing. How are you creating ZkHelixPropertyStore
> instance?
>
> public ZkHelixPropertyStore(ZkBaseDataAccessor<T> accessor, String root,
>       List<String> subscribedPaths) {
>     super(accessor, root, null, subscribedPaths);
> }
>
> This is right constructor. For subscribedPaths, you can simply pass in
> path to property store which is "/{clusterName}/PROPERTYSTORE"
>
>
> On Fri, Oct 23, 2015 at 10:06 AM, Hang Qi <ha...@gmail.com> wrote:
>
>> Hi All,
>>
>> We are using HelixPropertyStore in helix 0.6.4. The doc says "Helix
>> supports caching the data with a write-through cache", so if I have two
>> nodes A and B, if A made changes on some property in PropertyStore after B,
>> will B get latest one?  In our test, we kind of observe that B will still
>> use its cached version, is that expected, do we have a way to get latest
>> version on B?
>>
>> Besides, we notice following log, looks like we need to specify paths for
>> watchers, but we do not find a way how to do that in HelixPropertyStore.
>>
>> WARN  org.apache.helix.manager.zk.ZkCacheBaseDataAccessor  - ZkCachePaths
>> is null or empty. Will not start ZkCacheEventThread
>>
>> Moreover, do we support concurrent set on HelixPropertyStore? Just saw
>> following description on AutoFallbackPropertyStore: "Property store that
>> does auto fallback to an old location. Assuming no concurrent updates"
>>
>> Any suggestions ?
>>
>> Thanks
>> Hang Qi
>>
>
>


-- 
Qi hang

Re: Question about HelixPropertyStore

Posted by kishore g <g....@gmail.com>.
Hi Hang,

This api is a bit confusing. How are you creating ZkHelixPropertyStore
instance?

public ZkHelixPropertyStore(ZkBaseDataAccessor<T> accessor, String root,
      List<String> subscribedPaths) {
    super(accessor, root, null, subscribedPaths);
}

This is right constructor. For subscribedPaths, you can simply pass in path
to property store which is "/{clusterName}/PROPERTYSTORE"


On Fri, Oct 23, 2015 at 10:06 AM, Hang Qi <ha...@gmail.com> wrote:

> Hi All,
>
> We are using HelixPropertyStore in helix 0.6.4. The doc says "Helix
> supports caching the data with a write-through cache", so if I have two
> nodes A and B, if A made changes on some property in PropertyStore after B,
> will B get latest one?  In our test, we kind of observe that B will still
> use its cached version, is that expected, do we have a way to get latest
> version on B?
>
> Besides, we notice following log, looks like we need to specify paths for
> watchers, but we do not find a way how to do that in HelixPropertyStore.
>
> WARN  org.apache.helix.manager.zk.ZkCacheBaseDataAccessor  - ZkCachePaths
> is null or empty. Will not start ZkCacheEventThread
>
> Moreover, do we support concurrent set on HelixPropertyStore? Just saw
> following description on AutoFallbackPropertyStore: "Property store that
> does auto fallback to an old location. Assuming no concurrent updates"
>
> Any suggestions ?
>
> Thanks
> Hang Qi
>