Methods to discover weak consistency errors in an application, by executing, by a debugger, a first thread of the application, by, determining that a first instruction in the first thread specifies to store a first value at a first memory address, setting a current value stored in the first memory address as an old value for the first memory address in a container for the first thread, executing the first instruction to store the first value at the first memory address, and setting the first value as a new value for the first memory address in the container for the first thread. The debugger then executes a second thread of the application, by restoring old values in the containers for all other threads and restoring a new value for each memory address specified in a container for the second thread to its respective memory address.