Merge pull request #872 from huggingface/saving_schedules

Updating schedules for state_dict saving/loading

pytorch_transformers/optimization.py

@@ -36,13 +36,13 @@ class WarmupConstantSchedule(LambdaLR):
         Keeps learning rate schedule equal to 1. after warmup_steps.
     """
     def __init__(self, optimizer, warmup_steps, last_epoch=-1):
+        self.warmup_steps = warmup_steps
+        super(WarmupConstantSchedule, self).__init__(optimizer, self.lr_lambda, last_epoch=last_epoch)
 
-        def lr_lambda(step):
-            if step < warmup_steps:
-                return float(step) / float(max(1.0, warmup_steps))
-            return 1.
-
-        super(WarmupConstantSchedule, self).__init__(optimizer, lr_lambda, last_epoch=last_epoch)
+    def lr_lambda(self, step):
+        if step < self.warmup_steps:
+            return float(step) / float(max(1.0, self.warmup_steps))
+        return 1.
 
 
 class WarmupLinearSchedule(LambdaLR):
@@ -51,13 +51,14 @@ class WarmupLinearSchedule(LambdaLR):
         Linearly decreases learning rate from 1. to 0. over remaining `t_total - warmup_steps` steps.
     """
     def __init__(self, optimizer, warmup_steps, t_total, last_epoch=-1):
+        self.warmup_steps = warmup_steps
+        self.t_total = t_total
+        super(WarmupLinearSchedule, self).__init__(optimizer, self.lr_lambda, last_epoch=last_epoch)
 
-        def lr_lambda(step):
-            if step < warmup_steps:
-                return float(step) / float(max(1, warmup_steps))
-            return max(0.0, float(t_total - step) / float(max(1.0, t_total - warmup_steps)))
-
-        super(WarmupLinearSchedule, self).__init__(optimizer, lr_lambda, last_epoch=last_epoch)
+    def lr_lambda(self, step):
+        if step < self.warmup_steps:
+            return float(step) / float(max(1, self.warmup_steps))
+        return max(0.0, float(self.t_total - step) / float(max(1.0, self.t_total - self.warmup_steps)))
 
 
 class WarmupCosineSchedule(LambdaLR):
@@ -66,17 +67,19 @@ class WarmupCosineSchedule(LambdaLR):
         Decreases learning rate from 1. to 0. over remaining `t_total - warmup_steps` steps following a cosine curve.
         If `cycles` (default=0.5) is different from default, learning rate follows cosine function after warmup.
     """
-    warn_t_total = True
     def __init__(self, optimizer, warmup_steps, t_total, cycles=.5, last_epoch=-1):
+        self.warmup_steps = warmup_steps
+        self.t_total = t_total
+        self.cycles = cycles
+        super(WarmupCosineSchedule, self).__init__(optimizer, self.lr_lambda, last_epoch=last_epoch)
 
-        def lr_lambda(step):
-            if step < warmup_steps:
-                return float(step) / float(max(1.0, warmup_steps))
-            else:
-                progress = float(step - warmup_steps) / float(max(1, t_total - warmup_steps))   # progress after warmup
-                return max(0.0, 0.5 * (1. + math.cos(math.pi * float(cycles) * 2.0 * progress)))
+    def lr_lambda(self, step):
+        if step < self.warmup_steps:
+            return float(step) / float(max(1.0, self.warmup_steps))
+        # progress after warmup
+        progress = float(step - self.warmup_steps) / float(max(1, self.t_total - self.warmup_steps))
+        return max(0.0, 0.5 * (1. + math.cos(math.pi * float(self.cycles) * 2.0 * progress)))
 
-        super(WarmupCosineSchedule, self).__init__(optimizer, lr_lambda, last_epoch=last_epoch)
 
 class WarmupCosineWithHardRestartsSchedule(LambdaLR):
     """ Linear warmup and then cosine cycles with hard restarts.
@@ -85,17 +88,20 @@ class WarmupCosineWithHardRestartsSchedule(LambdaLR):
         learning rate (with hard restarts).
     """
     def __init__(self, optimizer, warmup_steps, t_total, cycles=1., last_epoch=-1):
+        self.warmup_steps = warmup_steps
+        self.t_total = t_total
+        self.cycles = cycles
+        super(WarmupCosineWithHardRestartsSchedule, self).__init__(optimizer, self.lr_lambda, last_epoch=last_epoch)
+
+    def lr_lambda(self, step):
+        if step < self.warmup_steps:
+            return float(step) / float(max(1, self.warmup_steps))
+        # progress after warmup
+        progress = float(step - self.warmup_steps) / float(max(1, self.t_total - self.warmup_steps))
+        if progress >= 1.0:
+            return 0.0
+        return max(0.0, 0.5 * (1. + math.cos(math.pi * ((float(self.cycles) * progress) % 1.0))))
 
-        def lr_lambda(step):
-            if step < warmup_steps:
-                return float(step) / float(max(1, warmup_steps))
-            else:
-                progress = float(step - warmup_steps) / float(max(1, t_total - warmup_steps))   # progress after warmup
-                if progress >= 1.0:
-                    return 0.0
-                return max(0.0, 0.5 * (1. + math.cos(math.pi * ((float(cycles) * progress) % 1.0))))
-
-        super(WarmupCosineWithHardRestartsSchedule, self).__init__(optimizer, lr_lambda, last_epoch=last_epoch)
 
 
 class AdamW(Optimizer):

pytorch_transformers/tests/optimization_test.py

@@ -17,13 +17,14 @@ from __future__ import division
 from __future__ import print_function
 
 import unittest
+import os
 
 import torch
 
 from pytorch_transformers import (AdamW, ConstantLRSchedule, WarmupConstantSchedule,
                                   WarmupCosineSchedule, WarmupCosineWithHardRestartsSchedule, WarmupLinearSchedule)
 
-import numpy as np
+from .tokenization_tests_commons import TemporaryDirectory
 
 
 def unwrap_schedule(scheduler, num_steps=10):
@@ -33,6 +34,20 @@ def unwrap_schedule(scheduler, num_steps=10):
         lrs.append(scheduler.get_lr())
     return lrs
 
+def unwrap_and_save_reload_schedule(scheduler, num_steps=10):
+    lrs = []
+    for step in range(num_steps):
+        scheduler.step()
+        lrs.append(scheduler.get_lr())
+        if step == num_steps // 2:
+            with TemporaryDirectory() as tmpdirname:
+                file_name = os.path.join(tmpdirname, 'schedule.bin')
+                torch.save(scheduler.state_dict(), file_name)
+
+                state_dict = torch.load(file_name)
+                scheduler.load_state_dict(state_dict)
+    return lrs
+
 class OptimizationTest(unittest.TestCase):
 
     def assertListAlmostEqual(self, list1, list2, tol):
@@ -72,6 +87,10 @@ class ScheduleInitTest(unittest.TestCase):
         self.assertEqual(len(lrs[0]), 1)
         self.assertListEqual([l[0] for l in lrs], expected_learning_rates)
 
+        scheduler = ConstantLRSchedule(self.optimizer)
+        lrs_2 = unwrap_and_save_reload_schedule(scheduler, self.num_steps)
+        self.assertListEqual([l[0] for l in lrs], [l[0] for l in lrs_2])
+
     def test_warmup_constant_scheduler(self):
         scheduler = WarmupConstantSchedule(self.optimizer, warmup_steps=4)
         lrs = unwrap_schedule(scheduler, self.num_steps)
@@ -79,6 +98,10 @@ class ScheduleInitTest(unittest.TestCase):
         self.assertEqual(len(lrs[0]), 1)
         self.assertListEqual([l[0] for l in lrs], expected_learning_rates)
 
+        scheduler = WarmupConstantSchedule(self.optimizer, warmup_steps=4)
+        lrs_2 = unwrap_and_save_reload_schedule(scheduler, self.num_steps)
+        self.assertListEqual([l[0] for l in lrs], [l[0] for l in lrs_2])
+
     def test_warmup_linear_scheduler(self):
         scheduler = WarmupLinearSchedule(self.optimizer, warmup_steps=2, t_total=10)
         lrs = unwrap_schedule(scheduler, self.num_steps)
@@ -86,6 +109,10 @@ class ScheduleInitTest(unittest.TestCase):
         self.assertEqual(len(lrs[0]), 1)
         self.assertListEqual([l[0] for l in lrs], expected_learning_rates)
 
+        scheduler = WarmupLinearSchedule(self.optimizer, warmup_steps=2, t_total=10)
+        lrs_2 = unwrap_and_save_reload_schedule(scheduler, self.num_steps)
+        self.assertListEqual([l[0] for l in lrs], [l[0] for l in lrs_2])
+
     def test_warmup_cosine_scheduler(self):
         scheduler = WarmupCosineSchedule(self.optimizer, warmup_steps=2, t_total=10)
         lrs = unwrap_schedule(scheduler, self.num_steps)
@@ -93,6 +120,10 @@ class ScheduleInitTest(unittest.TestCase):
         self.assertEqual(len(lrs[0]), 1)
         self.assertListAlmostEqual([l[0] for l in lrs], expected_learning_rates, tol=1e-2)
 
+        scheduler = WarmupCosineSchedule(self.optimizer, warmup_steps=2, t_total=10)
+        lrs_2 = unwrap_and_save_reload_schedule(scheduler, self.num_steps)
+        self.assertListEqual([l[0] for l in lrs], [l[0] for l in lrs_2])
+
     def test_warmup_cosine_hard_restart_scheduler(self):
         scheduler = WarmupCosineWithHardRestartsSchedule(self.optimizer, warmup_steps=2, cycles=2, t_total=10)
         lrs = unwrap_schedule(scheduler, self.num_steps)
@@ -100,6 +131,9 @@ class ScheduleInitTest(unittest.TestCase):
         self.assertEqual(len(lrs[0]), 1)
         self.assertListAlmostEqual([l[0] for l in lrs], expected_learning_rates, tol=1e-2)
 
+        scheduler = WarmupCosineWithHardRestartsSchedule(self.optimizer, warmup_steps=2, cycles=2, t_total=10)
+        lrs_2 = unwrap_and_save_reload_schedule(scheduler, self.num_steps)
+        self.assertListEqual([l[0] for l in lrs], [l[0] for l in lrs_2])
 
 if __name__ == "__main__":
     unittest.main()