Database.update is not working as expected

Question

I am trying to write a code which will query account records and lock them using FOR UPDATE keyword and then I am also triggering another batch which will try tu update same record with some more records of account. But even after using Database.update(xyz,false) I am getting error lock for all other records as well even if we are using Database.update

Can anyone please help me. Below is sample code snippet:

First i am executing below code to lock the specific record:

Account act = [SELECT Id FROM Account WHERE Id = '0010I00002DmyzG' FOR UPDATE];
for (Integer index = 0; index < 44444; index ++ ) {
 for (Integer index1= 0; index1 < 44444; index1++ ) {

 }
}

Secondly I am executing below code to update the same record used above with two separate records but even if I am using database.update I am getting row lock error for other two records as well

Set<Id> cSet = new Set<Id>();
cSet.add('0010I00002DmyzG');
ctSet.add('0010I00002Dmyv7');
cSet.add('00128000009iR8y');

List<Account> ctrList = new List<Account>();
for (Account ct : [
 SELECT Active__c FROM Account WHERE Id IN :cSet]) {
 ct.Active__c = 'Yes';
 ctrList.add(ct);
}

Thanks

Answer 1

The row-locking mechanism will always throw an exception if a lock is not acquired in about ten seconds. This behavior helps prevent deadlocks/infinite loops. When using FOR UPDATE, you should be aware of that feature. If you think you'll need more time, you can catch the exception and try again.

Please note that you should always use FOR UPDATE for queries in which you plan to update records, and you should always lock parents before children, if applicable (e.g. Accounts first, Contacts second). As an example of your code, the following change would work:

Set<Id> cSet = new Set<Id>();
cSet.add('0010I00002DmyzG');
cSet.add('0010I00002Dmyv7');
cSet.add('00128000009iR8y');

while(true) {
  try {
    List<Account> ctrList = new List<Account>();
    for (Account ct : [
        SELECT Active__c FROM Account WHERE Id IN :cSet FOR UPDATE]) {
      ct.Active__c = 'Yes';
      ctrList.add(ct);
    }
    Database.update(ctrList, false);
    break; // Stop infinite loop
  } catch(QueryException e) {
}

By querying first, we make sure we get a row lock, or fail with an exception, which we retry until we reach governor limits or succeed.