# Assume that ins_thread, etc. already set up as in runner/multi_btree_heavy_stress.py
threads = ins_thread * 1 + upd_thread * 1 + read_thread * 2
workload = Workload(context, threads)

# Define a callback that will be called periodically
from wiredtiger import stat
class MyCallback(WorkloadCallback):
    def __init__(self):
        self.mult = 1
        self.dirty = 0

    def callback(self, workload, conn):
        session = conn.open_session()
        cur = session.open_cursor('statistics:', None, None)
        dirty = cur[stat.conn.cache_eviction_dirty][2]
        new_dirty = self.dirty - dirty
        self.dirty = dirty
        session.close()
        if new_dirty < 100000:
            self.mult += 1
        elif self.mult > 2:
            self.mult -= 1
        threads = ins_thread * self.mult + upd_thread * self.mult + read_thread * 1
        workload.reset_threads(threads)

workload.options.callback = MyCallback()
workload.options.callback_time = 1  # every second
workload.options.run_time = 30
workload.options.report_interval = 1
workload.run(conn)