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Default Transaction Timeout

Asked 2009-08-28T16:45:18.017
42

I used to set Transaction timeouts by using TransactionOptions.Timeout, but have decided for ease of maintenance to use the config approach:

 <system.transactions>
    <defaultSettings timeout="00:01:00" />
  </system.transactions>

Of course, after putting this in, I wanted to test it was working, so reduced the timeout to 5 seconds, then ran a test that lasted longer than this - but the transaction does not appear to abort! If I adjust the test to set TransactionOptions.Timeout to 5 seconds, the test works as expected

After Investigating I think the problem appears to relate to TransactionOptions.Timeout, even though I'm no longer using it.

I still need to use TransactionOptions so I can set IsolationLevel, but I no longer set the Timeout value, if I look at this object after I create it, the timeout value is 00:00:00, which equates to infinity. Does this mean my value set in the config file is being ignored?

To summarise:

  • Is it impossible to mix the config setting, and use of TransactionOptions
  • If not, is there any way to extract the config setting at runtime, and use this to set the Timeout property
  • [Edit] OR Set the default isolation-level without using TransactionOptions
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3 Answers

53

You can mix system.transaction configuration settings and the use of the TransactionOption class, but there are some things you need to be aware of.

If you use the TransactionOption and specify a Timeout value, that value will be used over the system.transactions/defaultTimeout value.

The above is the crux of the problem in your case I think. You are using the TransactionOption to specify the isolation level, and as a side effect you are getting an infinite Timeout value because infinite is the default Timeout value for TransactionOption if its not specified. Though, I'm not quite sure why that is...it would make sense to default to the default Transaction Timeout.

You can implement your own TransactionOptions helper class that includes defaults that are read from app.config (if found) or default to reasonable values for a TransactionOption class that can be used.

In any case, you can still limit this by using the system.transaction/machineSettings/maxTimeout value. This is an administrative setting and can only be configured through the machine.config. You'll get a ConfigurationException if you try it from app/web.config.

<system.transactions>
    <machineSettings maxTimeout="00:00:30" />
</system.transactions>

With the maxTimeout set, no matter what timeout value you specify, the maximum value will be limited to the maxTimeout value. The default maxTimeout is 00:10:00, or 10 minutes, so you wouldn't actually ever have an infinite timeout on a transaction.

You can also set the transaction IsolationLevel explicitly on the database connection you are using within the transaction. Something like this?

   var connectionString = "Server=.;Database=master;Trusted_Connection=True;";
answered 2009-09-02T13:14:05.083
53

You can get the (validated) default timeout from the configuration using TransactionManager.DefaultTimeout.

TransactionOptions is a struct that encapsulates timeout and isolation level. When initializing a struct using the default constructor, it will always initialize the struct members to their default values:

TransactionOptions transactionOptions = new TransactionOptions();
transactionOptions.Timeout == default(TimeSpan); // TimeSpan.Zero
transactionOptions.IsolationLevel == default(IsolationLevel); // IsolationLevel.Serializable

If you want to specify an IsolationLevel and use the default timeout:

new TransactionOptions()
{
    IsolationLevel = IsolationLevel.Serializable, // Use whatever level you require
    Timeout = TransactionManager.DefaultTimeout
};
answered 2010-04-27T20:17:34.253
13

Per Reflector, the basic rules for setting a transaction time out with the constructors of TransactionScope are as follows:

The DefaultTimeOut is determined by the first rule from below that is satisfied:

  • if the constructor has a TimeSpan parameter, the DefaultTimeout is the that parameter
  • if the constructor has a TransactionOption parameter, the DefaultTimeout is transactionOption.TimeOut
  • if the constructor has a TransactionScopeOption parameter, the DefaultTimeout is scopeOption.TimeOut
  • if the constructor does not have timeout parameter, the DefaultTimeout is the value specified in the app or web config file.
  • otherwise, DefaultTimeOut is 1 minute.

The MaxTimeOut is 10 minutes unless another value is specified in the machine.config.

The effective timeout for the transaction is smaller of the MaxTimeOut and DefaultTimeOut that is greater than zero. If both MaxTimeOut and DefaultTimeOut are zero, the effective timeout is the number of ticks represented by long.MaxValue (the infinity).

If the TransactionScope instance does not create a new transaction either because a transaction is passed into its constructor, or because the transaction scope option does not require it (e.g., when an ambient transaction is present and the TransactionScopeOption is Required), but a timeOut parameter is still passed in the constructor, a timer is started. When the timeout period elapses, the underlying transaction's TimeOut() method is called. The DefaultTimeOut and MaxTimeOut properties are not used in this case.

If the transactionScopeOption == TransactionScopeOption.Supress, the timeout is ignored and has no effect.

It is also possible to define the MaxTimeOut in the app/web config fi

answered 2013-01-02T07:36:23.917

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