presto-main/src/main/java/io/prestosql/execution/buffer/OutputBufferMemoryManager.java/OutputBufferMemoryManager/getSystemMemoryContext
class OutputBufferMemoryManager:    private Optional<LocalMemoryContext> getSystemMemoryContext()
    {
        try {
            return Optional.of(systemMemoryContextSupplier.get());
        }
        catch (RuntimeException ignored) {
            // This is possible with races, e.g., a task is created and then immediately aborted,
            // so that the task context hasn't been created yet (as a result there's no memory context available).
        }
        return Optional.empty();
    }