IllegalReferenceCountException exception in TextRowDecoder

[unoexperto]

@rusher I'm having similar issue with version 1.1.1-rc.

I couldn't get to the bottom of this yet but I get IllegalReferenceCountException exception in TextRowDecoder.setPosition().

It happens in line

short type = this.buf.readUnsignedByte();

because reference count of RowDecoder.buf. I'm assuming you're reusing instance of ByteBuf. So far I can't find consistent pattern to reproduce it but I can say it happens when query returns a lot of rows (80K+ items).

Sadly I'm seeing that it doesn't happen when I slow down the application (using profiler for example). Race condition somewhere?

UPD: I thought maybe it's related to spring-projects/spring-framework#26060 so I upgraded to Netty 4.1.70 but it didn't help. That's too bad since it's no-go for production :( Interestingly enough inside AbstractByteBuf.ensureAccessible() call ((UnpooledSlicedByteBuf) this).buffer.refCnt() that works via ReferenceCountUpdater returns 0 but underlying volatile int refCnt field has 1. Ah... they have wacky code in counter updater. When count is one then treat it as zero https://github.com/netty/netty/blob/ea2742b4f628dfae9523c49b22472df921d1386c/common/src/main/java/io/netty/util/internal/ReferenceCountUpdater.java#L62 but why....

Originally posted by @unoexperto in #7 (comment)

[RamonVerbruggen]

Since updating to Spring Boot 2.7.0, I have the same (edit: reproducible) problem when using this r2dbc migrate tool
I'm not sure why a version 1.1.1-rc is used from spring boot, and I really hope this can be fixed before an official 1.1.1 release is made.

[RamonVerbruggen]

After some experimentation I found that the exact same software works correctly with the 1.0.3 release of the r2dbc-mariadb driver.

[rusher]

This is normally corrected in 1.1.2.
Could you confirm using SNAPSHOT version ?

(snapshot are available through sonatype snapshot repository)

<repositories>
    <repository>
        <id>sonatype-nexus-snapshots</id>
        <name>Sonatype Nexus Snapshots</name>
        <url>https://oss.sonatype.org/content/repositories/snapshots</url>
    </repository>
</repositories>

    <dependency>
        <groupId>org.mariadb</groupId>
        <artifactId>r2dbc-mariadb</artifactId>
        <version>1.1.2-SNAPSHOT</version>
    </dependency>

[RamonVerbruggen]

Thank you for your reply.
I have tested with 1.1.2-SNAPSHOT, and I still get the IllegalReferenceCountException.
Version 1.0.3 is working as expected.

[nkonev]

Seems I found how to fix it on r2dbc-migrate side.
The issue was produced by .last() operator https://github.com/nkonev/r2dbc-migrate/blob/5fbedb960980e2c7a25f481d9943510df6e61f1f/r2dbc-migrate-core/src/main/java/name/nkonev/r2dbc/migrate/core/R2dbcMigrate.java#L312

I need time to make new release

Try r2dbc-migrate 2.7.x

[RamonVerbruggen]

r2dbc-migrate 2.7.x works for me, but not in combination with mariadb driver version 1.1.1-rc
The error message is different, but I still get errors that I do not get with mariadb driver 1.0.3

Have not tried mariadb driver 1.1.2-SNAPSHOT with r2dbc-migrate 2.7.x

[nkonev]

I got IllegalReferenceCountException exception with mariadb driver version 1.1.1-rc in tests in r2dbc-migrate.
After I moved .last() operator to the different place the error gone and I released r2dbc-migrate 2.7.x

If you will get error with mariadb driver 1.1.2-SNAPSHOT and r2dbc-migrate 2.7.x please share new reproducer.

[RamonVerbruggen]

Sorry, my bad, let me rephrase:

With r2dbc-migrate 2.7.x and driver version 1.1.1-rc, migrate now runs fine for me, although I still get problems during later tests, that I do not get with driver 1.0.3. I will post a new issue for the driver when I get the repro figured out.

As far as I can tell, r2dbc-migrate was not the source of the problem, just the place where it showed up.

[serajin00]

I got 'refCnt: 0' exception when using 'r2dbc-mariadb:1.1.2' and also same with '1.1.1-rc'.
Only '1.0.3' have no problem.

Caused by: io.netty.util.IllegalReferenceCountException: refCnt: 0
	at io.netty.buffer.AbstractByteBuf.ensureAccessible(AbstractByteBuf.java:1454) ~[netty-buffer-4.1.82.Final.jar:4.1.82.Final]
	at io.netty.buffer.AbstractByteBuf.checkReadableBytes0(AbstractByteBuf.java:1440) ~[netty-buffer-4.1.82.Final.jar:4.1.82.Final]
	at io.netty.buffer.AbstractByteBuf.readByte(AbstractByteBuf.java:730) ~[netty-buffer-4.1.82.Final.jar:4.1.82.Final]
	at io.netty.buffer.AbstractByteBuf.readUnsignedByte(AbstractByteBuf.java:744) ~[netty-buffer-4.1.82.Final.jar:4.1.82.Final]
	at org.mariadb.r2dbc.codec.TextRowDecoder.setPosition(TextRowDecoder.java:82) ~[r2dbc-mariadb-1.1.2.jar:1.1.2]
	at org.mariadb.r2dbc.codec.TextRowDecoder.get(TextRowDecoder.java:23) ~[r2dbc-mariadb-1.1.2.jar:1.1.2]
	at org.mariadb.r2dbc.MariadbReadable.get(MariadbReadable.java:33) ~[r2dbc-mariadb-1.1.2.jar:1.1.2]
	at org.mariadb.r2dbc.MariadbReadable.get(MariadbReadable.java:70) ~[r2dbc-mariadb-1.1.2.jar:1.1.2]
	at io.r2dbc.spi.Readable.get(Readable.java:80) ~[r2dbc-spi-0.9.1.RELEASE.jar:na]
	at org.springframework.data.r2dbc.convert.MappingR2dbcConverter.readFrom(MappingR2dbcConverter.java:170) ~[spring-data-r2dbc-1.5.3.jar:1.5.3]
	... 54 common frames omitted

[Camsteack]

This is happening for me as well. Impossible to use the latest version of the driver, only 1.0.2 works.
Any fix on the way ?
Cheers !

[bacca87]

I get the same issue using micronaut and r2dbc-mariadb v1.1.2
micronaut-projects/micronaut-data#1806