Woonsan Ko created JCR-4369:
-------------------------------
Summary: Avoid S3 Incomplete Read Warning
Key: JCR-4369
URL: https://issues.apache.org/jira/browse/JCR-4369
Project: Jackrabbit Content Repository
Issue Type: Improvement
Components: jackrabbit-aws-ext
Reporter: Woonsan Ko
While using S3DataStore, the following logs are observed occasionally:
{noformat}
WARN [com.amazonaws.services.s3.internal.S3AbortableInputStream.close():178]
Not all bytes were read from the S3ObjectInputStream, aborting HTTP connection.
This is likely an error and may result in sub-optimal behavior. Request only
the bytes you need via a ranged GET or drain the input stream after use.
{noformat}
The warning logs are being left not only by both HTTP processing threads, but
also by background threads, which made me think of the possibility of some
'issues' in {{S3Backend}} implementation. Not just caused by a broken http
connection by client.
After looking at the code, I noticed that {{CachingDataStore#proactiveCaching}}
is enabled by default, which means the {{S3DataStore}} tries to _proactively_
download the binary content even when accessing metadata through
{{#getLastModified(...) and #getLength(...).
Anyway, the _minor_ problem is now, whenever the {{S3Backend}} reads content
(in other words get an input stream on an {{S3Object}}, it is recommended to
_read_ all data or _abort_ the input stream. Just closing the input stream is
not good enough in AWS SDK perspective, which gives a warning if the input
stream was not fully read or not aborted explicitly. See
{{S3AbortableInputStream#close()}} method. \[1\]
Therefore, {{org.apache.jackrabbit.core.data.LocalCache#store(String,
InputStream)}} (used by {{CachingDataStore#getStream(DataIdentifier)}}) could
be improved like the following:
- If local cache file doesn't exist or it's on purge mode, it works as it does:
Just copy everything to local cache file and close it.
- Otherwise, it should {{abort}} the input stream.
\[1\]
https://github.com/aws/aws-sdk-java/blob/master/aws-java-sdk-s3/src/main/java/com/amazonaws/services/s3/internal/S3AbortableInputStream.java#L174-L187
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