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Displaying posts with tag: error handling (reset)

Re-implementing udf_init_error in MySQL 5.5 and up
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To whom it may concern -

Today, I received an email from a user of the udf_init_error UDF (which resides in the lib_mysqludf_udf library). The purpose of this UDF is to generate an error condition, which can be used to abruptly terminate a trigger or stored procedure. As such it is a workaround for bug #11661. …

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Cluster - spins/contentions and thread stuck in..
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I get a number of question about contentions/"stuck in..". So here comes some explanation to:

  • Contention
  • Thread Stuck in
  • What you can do about it

In 99% of the cases the contentions written out in the out file of the data nodes (ndb_X_out.log) is nothing to pay attention to.

sendbufferpool waiting for lock, contentions: 6000 spins: 489200
sendbufferpool waiting for lock, contentions: 6200 spins: 494721

Each spin is read from the L1 cache (4 cycles on a Nehalem (3.2GHz), so about a nanosecond).
1 spin = 1.25E-09 seconds (1.25ns) …

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Node failure handling - take 2
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Jonas improved the node failure handling in MySQL Cluster 7.0.9 (and 6.3.29) so here comes a re-run of the a previous blog post. And the node failure handling time has improved a lot - see below.

I created in total 11345 tables, each with 128 columns, and then hit this bug.

When all tables were created, I stopped one node and measured how long time it takes for the other node to perform the node failure handling. Here is what was written into the cluster log …

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Node failure handling
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When a data node fails, the other data nodes must perform clean-up of the failed node.

E.g, to abort transactions in the PREPARE phase (Cluster uses a variant of the Two Phase Commit protocol) that has been started on the Data node that fails.
Various protocols (if the failed data node is the master) must also fail-over.

These things are carried out quite swiftly (configurable, but a couple of seconds by default but it also depends on the size of transactions that in the prepare phase that needs to be aborted).

I wanted …

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Showing entries 1 to 4

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