Read committed isolation level blocking

Question

I'm trying to understand and use spring transactional isolation level. I need to maximize concurrency of my application and I just need to be careful about dirty reads. Phantom read and other scenarios are really not required to be taken care. So decided to use Isolation.READ_COMMITTED for one of the most used transactional methods of my application. As per spring documenttion:

This level only prohibits a transaction from reading a row with uncommitted changes in it.

So here is the scenario I am facing that i believe is little different than above statement.

criticalMethod(customeId):

1. Read data of customer from table1
2. make some decision
3. add a new row for that customer in table1
4. carry on some long processing.....

So when this method gets called in parallel for two completely independently customers c1 and c2, if for c1 was on step 4 when method for c2 gets called. So my method call for c2 blocks at step 1 util method call for c1 finishes.

I simulated this scenario with eclipse debugging. I am able to query data from my database side on table1 for customer c2. As per the above documentation of spring, my second method call should not get blocked.

Am I missing something?

Here is my technology stack:

• Java: 8
• Spring : 4.3.7
• Database: SqlServer 2012
• ORM: Mybatis 3.4.2
• mybatis spring version : 1.3.1