What are some common scenarios in System Verilog where race conditions can occur?

In SystemVerilog, race conditions can occur in various scenarios where multiple processes or threads access and modify shared variables simultaneously. Here are some common scenarios where race conditions can occur:

1. Procedural Blocks: Race conditions can occur when using procedural blocks such as always and initial blocks, where multiple processes operate on the same variable in different parts of the code .
2. Blocking and Non-blocking Assignments: Race conditions can arise when there is a mix of blocking and non-blocking assignments in the same code block. For example, if one process writes to a variable using a blocking assignment, and another process reads the same variable using a non-blocking assignment, a race condition can occur .
3. Incomplete Sensitivity List: If the sensitivity list of an always block is not properly defined, it can lead to race conditions. For instance, if the sensitivity list does not include all the variables that the block depends on, the block may not execute when expected, resulting in race conditions .
4. Edge-Sensitive Events: When using edge-sensitive events, such as @(posedge clk), race conditions can occur if one process writes to a variable while another process reads the same variable using an event control statement. It is recommended to use non-blocking assignments between synchronous processes to avoid race conditions .
5. Multiple Threads or Processes: When multiple threads or processes run in parallel and are synchronized to the same event, there can be a race condition between reading the old value or the updated value from a blocking assignment. To prevent this, non-blocking assignments should be used when one process writes and another process reads the same variable synchronized to the same clock .

It is important to note that these are just a few examples of common scenarios where race conditions can occur in System Verilog. It is crucial to carefully design and synchronize processes to avoid race conditions and ensure the correct behavior of the hardware design or verification code.