[jira] [Commented] (AVRO-1781) Schema.parse is not thread safe

["Sean Busbey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AVRO-1781?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15092283#comment-15092283 ] 

Sean Busbey commented on AVRO-1781:
-----------------------------------

2 main approaches I see:

* externalize the cache and store one per Schema.Parser instance, so you get caching if you reuse and the app can decide on parallelism trade-offs
* switch to using a R/W lock based cache so that it is threadsafe.

> Schema.parse is not thread safe
> -------------------------------
>
>                 Key: AVRO-1781
>                 URL: https://issues.apache.org/jira/browse/AVRO-1781
>             Project: Avro
>          Issue Type: Bug
>          Components: java
>    Affects Versions: 1.8.0
>            Reporter: Sean Busbey
>            Priority: Blocker
>             Fix For: 1.8.0
>
>
> Post AVRO-1497, Schema.parse calls {{LogicalTypes.fromSchemaIgnoreInvalid}} on any schema that is expressed as a JSON object (anything except bare primitives).
> That static method relies on a static cache based on WeakIdentityHashMap (WIHM).
> WIHM clearly states that it isn't threadsafe [ref|https://github.com/apache/avro/blob/branch-1.8/lang/java/avro/src/main/java/org/apache/avro/util/WeakIdentityHashMap.java#L42]
> {code}
>  * 
>  * Note that this implementation is not synchronized.
>  * </b>
>  */
> public class WeakIdentityHashMap<K, V> implements Map<K, V> {
> {code}
> All of the Schema.Parser instances use that same static Schema.parse method.
> The end result is that as-is it's only safe to have a single thread parsing schemas in a given JVM.



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