Windows service not reading sql table

[timb]

Hi,
I have created a windows service which is responsible for running
certain tasks when they are scheduled to run. The service monitors a sql
table and runs a task when the task scheduled time is overdue. This service
is installed at several sites and on 4 out of 5 sites runs the tasks
correctly on schedule. However on some other sites the task will run one
night but then not run the next night and not subsequent nights. If i stop
and start the service on these sites the tasks run immediately. I am also
logging any error messages to the event log and i receive no errors on these
sites. The timer event occurs every 10 seconds.

1/Is setting objects to null the correct way to tell the GC that the object
is ready for Garbage collection?
2/Any ideas on why the service appears not to be reading the table under
some circumstances.
private static void Timer_Elapsed(o bject sender,
System.Timers.E lapsedEventArgs e)

{

// Poll epossync schedules table for jobs.

Timer.Enabled = false;

SQL.SqlDataRead er DR = null;

try

{

if (DR != null)

{

DR.Close();

DR = null;

}

DR = Utils.GetDataRe ader(cnEposSync ,

"Select Top 1 * from ScheduledTasks Where CompletedDate is null and
scheduledfor < getdate() Order By ScheduledFor");

if (DR.Read())

{

// Found Job run tasks

//.....here is where i run the tasks

//run task

DR.Close();

SQL.SqlCommand SQLcmd = new System.Data.Sql Client.SqlComma nd("Update
ScheduledTasks set CompletedDate = getdate() Where Scheduleid = "

+ id,cnEposSync);

// unrem this line to update table

SQLcmd.ExecuteN onQuery();

}

}

catch (Exception ex)

{

Utils.LogEvent( "Error in Timer_Elapsed : " +
ex.Message,Syst em.Diagnostics. EventLogEntryTy pe.Error);

}

finally

{

DR.Close();

DR = null;

}

Timer.Enabled = true;

}
Thanks in advance

--
TimB

[Eliyahu Goldin]

May be there is a network problem that causes the network to go down and the
service is unable to reconnect to the network when it is back up?

"timb" <ti**@test.co m> wrote in message
news:OD******** ******@TK2MSFTN GP12.phx.gbl...

Hi,
I have created a windows service which is responsible for running
certain tasks when they are scheduled to run. The service monitors a sql
table and runs a task when the task scheduled time is overdue. This service is installed at several sites and on 4 out of 5 sites runs the tasks
correctly on schedule. However on some other sites the task will run one
night but then not run the next night and not subsequent nights. If i stop and start the service on these sites the tasks run immediately. I am also
logging any error messages to the event log and i receive no errors on these sites. The timer event occurs every 10 seconds.

1/Is setting objects to null the correct way to tell the GC that the object is ready for Garbage collection?
2/Any ideas on why the service appears not to be reading the table under
some circumstances.
private static void Timer_Elapsed(o bject sender,
System.Timers.E lapsedEventArgs e)

{

// Poll epossync schedules table for jobs.

Timer.Enabled = false;

SQL.SqlDataRead er DR = null;

try

{

if (DR != null)

{

DR.Close();

DR = null;

}

DR = Utils.GetDataRe ader(cnEposSync ,

"Select Top 1 * from ScheduledTasks Where CompletedDate is null and
scheduledfor < getdate() Order By ScheduledFor");

if (DR.Read())

{

// Found Job run tasks

//.....here is where i run the tasks

//run task

DR.Close();

SQL.SqlCommand SQLcmd = new System.Data.Sql Client.SqlComma nd("Update
ScheduledTasks set CompletedDate = getdate() Where Scheduleid = "

+ id,cnEposSync);

// unrem this line to update table

SQLcmd.ExecuteN onQuery();

}

}

catch (Exception ex)

{

Utils.LogEvent( "Error in Timer_Elapsed : " +
ex.Message,Syst em.Diagnostics. EventLogEntryTy pe.Error);

}

finally

{

DR.Close();

DR = null;

}

Timer.Enabled = true;

}
Thanks in advance

--
TimB

[Richard]

>1/Is setting objects to null the correct way to tell the
GC that the object

is ready for Garbage collection?
Technically you don't need to set objects to null in order
for them to be garbage collected. The garbage collector
builds a dependancy graph of rooted {in use} objects each
time a GC cycle occurs, any unrooted objects will not be
in the graph and thus are subject to collection...
2/Any ideas on why the service appears not to be reading the table undersome circumstances.

Can you enable SQL Server logging on the offending
machine? If so the SQL Server log will tell you date/time
and text of executed queries and you could narrow down the
problem a bit...

How long are the timers running? Days? Weeks? Perhaps you
could try destroying the timer and recreating it more
frequently...

--Richard

[timb]

Thanks,
however this is unlikely to be the problem as the sql server is
the same server with this application installed.

"Eliyahu Goldin" <re************ *@monarchmed.co m> wrote in message
news:e3******** ******@TK2MSFTN GP09.phx.gbl...

May be there is a network problem that causes the network to go down and the service is unable to reconnect to the network when it is back up?

"timb" <ti**@test.co m> wrote in message
news:OD******** ******@TK2MSFTN GP12.phx.gbl...

Hi,
I have created a windows service which is responsible for running
certain tasks when they are scheduled to run. The service monitors a sql table and runs a task when the task scheduled time is overdue. This

service

is installed at several sites and on 4 out of 5 sites runs the tasks
correctly on schedule. However on some other sites the task will run one night but then not run the next night and not subsequent nights. If i

stop

and start the service on these sites the tasks run immediately. I am also logging any error messages to the event log and i receive no errors on

these

sites. The timer event occurs every 10 seconds.

1/Is setting objects to null the correct way to tell the GC that the

object

is ready for Garbage collection?
2/Any ideas on why the service appears not to be reading the table under
some circumstances.
private static void Timer_Elapsed(o bject sender,
System.Timers.E lapsedEventArgs e)

{

// Poll epossync schedules table for jobs.

Timer.Enabled = false;

SQL.SqlDataRead er DR = null;

try

{

if (DR != null)

{

DR.Close();

DR = null;

}

DR = Utils.GetDataRe ader(cnEposSync ,

"Select Top 1 * from ScheduledTasks Where CompletedDate is null and
scheduledfor < getdate() Order By ScheduledFor");

if (DR.Read())

{

// Found Job run tasks

//.....here is where i run the tasks

//run task

DR.Close();

SQL.SqlCommand SQLcmd = new System.Data.Sql Client.SqlComma nd("Update
ScheduledTasks set CompletedDate = getdate() Where Scheduleid = "

+ id,cnEposSync);

// unrem this line to update table

SQLcmd.ExecuteN onQuery();

}

}

catch (Exception ex)

{

Utils.LogEvent( "Error in Timer_Elapsed : " +
ex.Message,Syst em.Diagnostics. EventLogEntryTy pe.Error);

}

finally

{

DR.Close();

DR = null;

}

Timer.Enabled = true;

}
Thanks in advance

--
TimB