Check if an error occur during batch process

Question

Good day everyone, I create a batch process class. The problem I have at the moment, is that how will I check if there is an error encountered during the batch iteration. In my case, I've tried to process a batch with 8 iterations. From 1 to 6 there is no error. But during the 7th iteration, an error occur saying Too many query rows: 50001. My question is how will I check if some problem occur in the batch ? So far what I've tried are the following.

1. I put try and catch in my executable class and add variable to check if it enter the catch statement.but it seems it is not working.

2.I also try to put system.debug(); inside my finish class but it seems that when an error occured it will not read the finish method. I also try to add query in my finish which is something like this:

AsyncApexJob batchResult = [Select Id, Status, NumberOfErrors, JobItemsProcessed,  
    TotalJobItems, CreatedBy.Email, ExtendedStatus  
      from AsyncApexJob where Id = :bc.getJobId()];

But still it doesn't work.

What is the best way to fix my problem. Please help.

Answer 1

The last paragraph of this Exception Statements documentation explains why your try/catch doesn't help in this case:

Exceptions that Can’t be Caught

Some special types of built-in exceptions can’t be caught. Those exceptions are associated with critical situations in the Force.com platform. These situations require the abortion of code execution and don’t allow for execution to resume through exception handling. One such exception is the limit exception (System.LimitException) that the runtime throws if a governor limit has been exceeded, such as when the maximum number of SOQL queries issued has been exceeded. Other examples are exceptions thrown when assertion statements fail (through System.assert methods) or license exceptions.

When exceptions are uncatchable, catch blocks, as well as finally blocks if any, aren’t executed.

So as it is not possible to handle governor limit exceptions you have to come up with a code design that avoids them.

The quick fix is to try reducing your batch size: keep halving it until the code works then halve it one or two more times to provide some headroom.

But the real fix may be to change the query structure so that the number of rows returned is predictable. For example, querying child objects of the object that the batch runs over results in an unpredictable number of rows; instead making the child object the object that the batch runs over can result in a predictable number of rows and so guarantee that the governor limit exception won't happen. But exactly what approach you need to take depends on the details of what you are trying to accomplish.

PS

An example of re-throwing (see comment thread):

try {
    ...
} catch (Exception e) {
    // Do whatever error reporting/processing you want here
    // Then re-throw so the error also appears in AsyncApexJob
    throw e;
}