How can I capture Heap Dumps for other users?

Question

Some of my users are experiencing a strange behavior that I can't yet reproduce in a Sandbox, so I'm trying to monitor the bug more closely in our production database.

Since I'm in a production database, I can't edit the code to add new System.debug() calls. Instead, I'd like to use Heap Dumps to inspect the heap and state at various points, but I can't figure out how to collect them.

I'm monitoring a user's debug logs with the APEX_CODE filters set to 'Finest'. Logged in as myself, I have the Developer Console open with 2 heap dump locations set. But no heap dumps are captured, even though I can see from the debug logs that the code is being run.

How can I capture these dumps, or do you have other recommended debugging techniques?

Answer 1

The new Tooling API has the ApexExecutionOverlayAction object.

Specifies an Apex code snippet or SOQL query to execute at a specific line of code in an Apex class or trigger and optionally generate a heap dump.

You could use this to capture the heap dump for the required user.

Specifically, try setting:

• ActionScriptType to 'None'
• ExecutableEntityId to the Apex class Id
• ExpirationDate to some time in the future. Maybe an hour out
• IsDumpingHeap to true
• Iteration to 1
• The Line to "The line number of the heap dump marker"
• the ScopeId to the required UserId

I hacked something together in a .NET to try it out.

SforceService toolingService = // Get an instance of the ToolingService

string apexClassId = "01p70000CLASSID";

// This is the session owners UserId
//string heapUserId = "005700000000FOO";
// This is an Id of another user in the Org
string heapUserId = "005700000000BAR";

int heapDumpLine = 27;

ApexExecutionOverlayAction apexExecutionOverlayAction = new SalesforceTooling.ApexExecutionOverlayAction();
apexExecutionOverlayAction.ActionScriptType = "None";
apexExecutionOverlayAction.ExecutableEntityId = apexClassId;

apexExecutionOverlayAction.IsDumpingHeap = true;
apexExecutionOverlayAction.IsDumpingHeapSpecified = true;

apexExecutionOverlayAction.Iteration = 1;
apexExecutionOverlayAction.IterationSpecified = true;

apexExecutionOverlayAction.Line = heapDumpLine;
apexExecutionOverlayAction.LineSpecified = true;

apexExecutionOverlayAction.ScopeId = heapUserId;

SaveResult[] results = toolingService.create(new sObject[] { apexExecutionOverlayAction });
SaveResult triggerSaveResult = results[0];
if (!triggerSaveResult.success)
{
    Assert.Fail(triggerSaveResult.errors[0].message);
}
Assert.IsTrue(triggerSaveResult.success);

Note that this didn't make the Heap Dump Location appear in the developer console for the session owner. I logged in as the target user, but it appears I've broken the developer console for that user:

However, after hitting the dump point you can pull the resulting dump out from the ToolingService using the ApexLog. E.g.

QueryResult apexdumpLogResult = toolingService.query("Select Id, Application, DurationMilliseconds, Location, LogUserId, Operation from ApexLog where Location = 'HeapDump'");