On 09/30/2011 12:59 PM, Mark Rotteveel wrote:
> True, but making sure that you always lock resources in the same order,
> is the only sure way to prevent deadlocks.
I think I see the problem:
In Version10/GdsTransaction.cs (copy/paste from the Sourceforge SVN
browser, so excuse the formatting)
186 public void Rollback()
187 {
188 this.CheckTransactionState();
189
190 lock (this.database.SyncObject)
191 {
192 try
193 {
194 this.database.Write(IscCodes.op_rollback);
195 this.database.Write(this.handle);
196 this.database.Flush();
197
198 this.database.ReadResponse();
199
200 this.database.TransactionCount--;
201
202 if (this.Update != null)
203 {
204 this.Update(this, new EventArgs());
205 }
206
207 this.state = TransactionState.NoTransaction;
208 }
209 catch (IOException)
210 {
211 throw new IscException(IscCodes.isc_net_read_err);
212 }
213 }
214 }
The SyncObject lock is to protect the calls to this.database.Write etc.
(lines 194-200) but it also covers the transaction's state change (lines
202-207) which it shouldn't and is the point the deadlock occurs.
Something like this may be better:
public void Rollback()
{
this.CheckTransactionState();
lock (aNewPrivateTransactionLockObject)
{
try
{
// Make sure this sequence of actions on the DB object
isn't broken
lock (this.database.SyncObject)
{
this.database.Write(IscCodes.op_rollback);
this.database.Write(this.handle);
this.database.Flush();
this.database.ReadResponse();
this.database.TransactionCount--;
}
if (this.Update != null)
{
this.Update(this, new EventArgs());
}
this.state = TransactionState.NoTransaction;
}
...etc...
}
}
Similar changes would need to be made to the other functions in this
class (Commit, RollbackRetaining, etc...)
Scott
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