[ 
https://issues.apache.org/jira/browse/HDDS-9582?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Attila Doroszlai updated HDDS-9582:
-----------------------------------
    Description: 
OM transport factory creation logic:

{code:title=https://github.com/apache/ozone/blob/0b377f7620b4795031a517a7d5a48c5995210d35/hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/protocolPB/OmTransportFactory.java#L48-L66}
      // if configured transport class is different than the default
      // OmTransportFactory (Hadoop3OmTransportFactory), then
      // check service loader for transport class and instantiate it
      if (conf
          .get(OZONE_OM_TRANSPORT_CLASS,
              OZONE_OM_TRANSPORT_CLASS_DEFAULT) !=
          OZONE_OM_TRANSPORT_CLASS_DEFAULT) {
        ServiceLoader<OmTransportFactory> transportFactoryServiceLoader =
            ServiceLoader.load(OmTransportFactory.class);
        Iterator<OmTransportFactory> iterator =
            transportFactoryServiceLoader.iterator();
        if (iterator.hasNext()) {
          return iterator.next();
        }
      }
      return OmTransportFactory.class.getClassLoader()
          .loadClass(OZONE_OM_TRANSPORT_CLASS_DEFAULT)
          .asSubclass(OmTransportFactory.class)
          .newInstance();
{code}

There are several problems:

# Based on the code above, {{ServiceLoader}} is intended to be invoked only if 
non-default transport is configured.  This is wrong, since we need to use 
specific transport for Hadoop 2 for compatibility, regardless of the OM 
transport setting.  This is not caught by existing acceptance tests because we 
don't test Hadoop 2.7 with security enabled.
# Configuring some specific transport in {{ozone-site.xml}} is not enough for 
it to be applied, the class has to be set in {{META-INF/services}}, too.
# Comparison of actual vs. default setting uses reference equality instead of 
{{equals(...)}}.  Thus {{ServiceLoader}} is always invoked if 
{{ozone.om.transport.class}} has any value in {{ozone-default.xml}}.
# Default setting does not match in XML and Java constant (this is being 
changed in HDDS-9446, though).

I think we should prefer implementations in this order:

 * found via service loader
 * set in configuration
 * default

  was:
OM transport factory creation logic:

{code:title=https://github.com/apache/ozone/blob/0b377f7620b4795031a517a7d5a48c5995210d35/hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/protocolPB/OmTransportFactory.java#L48-L66}
      // if configured transport class is different than the default
      // OmTransportFactory (Hadoop3OmTransportFactory), then
      // check service loader for transport class and instantiate it
      if (conf
          .get(OZONE_OM_TRANSPORT_CLASS,
              OZONE_OM_TRANSPORT_CLASS_DEFAULT) !=
          OZONE_OM_TRANSPORT_CLASS_DEFAULT) {
        ServiceLoader<OmTransportFactory> transportFactoryServiceLoader =
            ServiceLoader.load(OmTransportFactory.class);
        Iterator<OmTransportFactory> iterator =
            transportFactoryServiceLoader.iterator();
        if (iterator.hasNext()) {
          return iterator.next();
        }
      }
      return OmTransportFactory.class.getClassLoader()
          .loadClass(OZONE_OM_TRANSPORT_CLASS_DEFAULT)
          .asSubclass(OmTransportFactory.class)
          .newInstance();
{code}

There are several problems:

# Based on the code above, {{ServiceLoader}} is intended to be invoked only if 
non-default transport is configured.  This is wrong, since we need to use 
specific transport for Hadoop 2 for compatibility, regardless of the OM 
transport setting.  This is not caught by existing acceptance tests because we 
don't test Hadoop 2.7 with security enabled.
# Configuring some specific transport in {{ozone-site.xml}} is not enough for 
it to be applied, the class has to be set in {{META-INF/services}}, too.
# Comparison of actual vs. default setting uses reference equality instead of 
{{equals(...)}}.  Thus {{ServiceLoader}} is always invoked if 
{{ozone.om.transport.class}} has any value in {{ozone-default.xml}}.
# Default setting does not match in XML and Java constant (this is being 
changed in HDDS-9446, though).


> OM transport factory configuration mismatch
> -------------------------------------------
>
>                 Key: HDDS-9582
>                 URL: https://issues.apache.org/jira/browse/HDDS-9582
>             Project: Apache Ozone
>          Issue Type: Bug
>    Affects Versions: 1.4.0
>            Reporter: Attila Doroszlai
>            Priority: Critical
>
> OM transport factory creation logic:
> {code:title=https://github.com/apache/ozone/blob/0b377f7620b4795031a517a7d5a48c5995210d35/hadoop-ozone/common/src/main/java/org/apache/hadoop/ozone/om/protocolPB/OmTransportFactory.java#L48-L66}
>       // if configured transport class is different than the default
>       // OmTransportFactory (Hadoop3OmTransportFactory), then
>       // check service loader for transport class and instantiate it
>       if (conf
>           .get(OZONE_OM_TRANSPORT_CLASS,
>               OZONE_OM_TRANSPORT_CLASS_DEFAULT) !=
>           OZONE_OM_TRANSPORT_CLASS_DEFAULT) {
>         ServiceLoader<OmTransportFactory> transportFactoryServiceLoader =
>             ServiceLoader.load(OmTransportFactory.class);
>         Iterator<OmTransportFactory> iterator =
>             transportFactoryServiceLoader.iterator();
>         if (iterator.hasNext()) {
>           return iterator.next();
>         }
>       }
>       return OmTransportFactory.class.getClassLoader()
>           .loadClass(OZONE_OM_TRANSPORT_CLASS_DEFAULT)
>           .asSubclass(OmTransportFactory.class)
>           .newInstance();
> {code}
> There are several problems:
> # Based on the code above, {{ServiceLoader}} is intended to be invoked only 
> if non-default transport is configured.  This is wrong, since we need to use 
> specific transport for Hadoop 2 for compatibility, regardless of the OM 
> transport setting.  This is not caught by existing acceptance tests because 
> we don't test Hadoop 2.7 with security enabled.
> # Configuring some specific transport in {{ozone-site.xml}} is not enough for 
> it to be applied, the class has to be set in {{META-INF/services}}, too.
> # Comparison of actual vs. default setting uses reference equality instead of 
> {{equals(...)}}.  Thus {{ServiceLoader}} is always invoked if 
> {{ozone.om.transport.class}} has any value in {{ozone-default.xml}}.
> # Default setting does not match in XML and Java constant (this is being 
> changed in HDDS-9446, though).
> I think we should prefer implementations in this order:
>  * found via service loader
>  * set in configuration
>  * default



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