Notes

2019-02-28 21:36 UTC

Fun MySQL fact of the day: chaos without `ORDER BY`

ANSI SQL-92 states that the order of a result set in the absence of an ORDER BY is implementation specific. This means that the same query without an ORDER BY clause run n times may return rows in n different orders. ... read more

2019-02-27 21:55 UTC

Fun MySQL fact of the day: no nested transactions

Nested transactions allow a client to begin and end multiple transactions within an outer transaction (within an outer transaction (within an outer transaction (within an outer transaction ...))). When would you use it? This type of mechanism is necessary to accomplish a pure Component Based Architecture. However, excepting BerkleyDB, nearly ... read more

2019-02-26 21:08 UTC

Fun MySQL fact of the day: `sync_binlog` is a counter

The D in ACID stands for Durability, which is the property that guarantees a committed transaction will be permanently recorded. Perfect durability is impossible, but MySQL allows us to improve our ability to offer this guarantee this through the sync_binlog flag. ... read more

2016-05-23 00:44 UTC

An In-Memory CSS Compressor For django-pipeline

I recently discovered the convenience of the django-pipeline library when attempting to reduce the asset size of a Django project. Currently, this library only seems to support external CSS compressors, such as Yuglify and YUI. While I have no objection to these specific tools, I simply do not want to ... read more

2016-05-13 00:37 UTC

Disable Artifact Archiving With Jenkins DSL

Out of the box, the Jenkins DSL project doesn't currently provide a way of disabling artifact archiving. For projects with large outputs built on slave nodes, this can cause dramatic slowdowns as gigabytes of data are sent back to the master. Luckily, the configure block can be used to disable ... read more

2016-03-28 03:32 UTC

Freeing MappedByteBuffer

While investigating a production bug that indicated that the operating system of a server running only a JVM continually ran out of memory under a specific set of circumstances, I discovered a very interesting idiosyncrasy of the JVM. Specifically, memory allocated with mmap through the MappedByteBuffer (the super class of ... read more

2015-03-02 02:45 UTC

Dropwizard IT Port Randomisation

Dropwizard's testing package includes a @ClassRule, DropwizardAppRule, that may be used to create end-to-end integration tests. However, you may rapidly discover that parallel test execution is severely impaired, as each test attempts to use the same application and admin ports as another. You can get around this by ... read more

2014-03-29 14:26 UTC

Retain Your CDI Qualifiers

The CDI specifications is very clear in its definition of qualifiers: ... read more

2013-07-22 04:59 UTC

Finally, Rollback Your Transaction

Lately, I've been working with code that exhibits a fairly poor practice: programmatic transactions (namely Spring) don't always get committed or rolled-back, even though the code appears correct. Consider the following contrived scenario: ... read more

2013-05-02 03:40 UTC

Enum Hash Codes Are Non-Deterministic

An annoying discovery: Java Enum objects have non-deterministic hash codes. Specifically, a hash code is the Enum's identity (or memory address). ... read more

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