diff --git a/HISTORY.rst b/HISTORY.rst
index 3be87853..efc1d3d0 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -1,5 +1,13 @@
 History
 =======
+2.1 (2020-07-05)
+-----------------
+* Global SummaryWriter that mimics python's default logger class, concurrent write is supported.
+* 200x speed up for add_audio. Please install the soundfile package for this feature.
+* Supports jax tensors.
+* The add_graph function is delegated to the one in torch.utils.tensorboard.
+* Bug fixes, see the commit log in Github.
+
 2.0 (2019-12-31)
 -----------------
 * Now you can tag Hparams trials with custom name instead of the default epoch time
diff --git a/README.md b/README.md
index d5ceec9d..81c01362 100644
--- a/README.md
+++ b/README.md
@@ -8,16 +8,15 @@
 
 Write TensorBoard events with simple function call.
 
+The current release (v2.1) is tested on anaconda3, with PyTorch 1.5.1 / torchvision 0.6.1 / tensorboard 2.2.2.
+
 * Support `scalar`, `image`, `figure`, `histogram`, `audio`, `text`, `graph`, `onnx_graph`, `embedding`, `pr_curve`, `mesh`, `hyper-parameters`
   and `video` summaries.
 
-* requirement for `demo_graph.py` is tensorboardX>=1.9 and pytorch>=1.3
-
 * [FAQ](https://github.com/lanpa/tensorboardX/wiki)
 
-## Install
 
-Tested on anaconda2 / anaconda3, with PyTorch 1.3.1 / torchvision 0.4.1 / tensorboard 2.0.0
+## Install
 
 `pip install tensorboardX`
 
@@ -25,15 +24,20 @@ or build from source:
 
 `pip install 'git+https://github.com/lanpa/tensorboardX'`
 
+You can optionally install [`crc32c`](https://github.com/ICRAR/crc32c) to speed up.
+
+`pip install crc32c`
 
-You can optionally install [`crc32c`](https://github.com/ICRAR/crc32c) to speed up saving a large amount of data.
+Starting from tensorboardX 2.1, You need to install `soundfile` for the `add_audio()` function (200x speedup).
 
+`pip install soundfile`
 
 ## Example
 
 * Clone the files in https://github.com/lanpa/tensorboardX/tree/master/examples
 * Run the demo script: e.g. `python examples/demo.py`
-* Use TensorBoard with `tensorboard --logdir runs`  (needs to install TensorFlow)
+* Start TensorBoard with `tensorboard --logdir runs`  
+
 
 ```python
 # demo.py
diff --git a/examples/demo.py b/examples/demo.py
index b0ebc1bf..ff589d06 100644
--- a/examples/demo.py
+++ b/examples/demo.py
@@ -6,6 +6,12 @@
 from tensorboardX import SummaryWriter
 import datetime
 
+try:
+    import soundfile
+    skip_audio = False
+except ImportError:
+    skip_audio = True
+
 resnet18 = models.resnet18(False)
 writer = SummaryWriter()
 sample_rate = 44100
@@ -37,12 +43,13 @@
              torch.Tensor([[10, 10, 100, 100], [101, 101, 200, 200]]),
              n_iter, 
              labels=['abcde' + str(n_iter), 'fgh' + str(n_iter)])
-        x = torch.zeros(sample_rate * 2)
-        for i in range(x.size(0)):
-            # sound amplitude should in [-1, 1]
-            x[i] = np.cos(freqs[n_iter // 10] * np.pi *
-                          float(i) / float(sample_rate))
-        writer.add_audio('myAudio', x, n_iter)
+        if not skip_audio:
+            x = torch.zeros(sample_rate * 2)
+            for i in range(x.size(0)):
+                # sound amplitude should in [-1, 1]
+                x[i] = np.cos(freqs[n_iter // 10] * np.pi *
+                            float(i) / float(sample_rate))
+            writer.add_audio('myAudio', x, n_iter)
         writer.add_text('Text', 'text logged at step:' + str(n_iter), n_iter)
         writer.add_text('markdown Text', '''a|b\n-|-\nc|d''', n_iter)
         for name, param in resnet18.named_parameters():
diff --git a/setup.py b/setup.py
index 190fadaf..77781a34 100644
--- a/setup.py
+++ b/setup.py
@@ -3,6 +3,7 @@
 
 import subprocess
 import os
+import sys
 from setuptools import setup, find_packages
 from setuptools.command.develop import develop
 from setuptools.command.install import install
@@ -30,16 +31,16 @@ def run(self):
 with open('HISTORY.rst') as history_file:
     history = history_file.read()
 
-preparing_PyPI_package = False
-version_git = version = '2.0'
+preparing_PyPI_package = 'sdist' in sys.argv or 'bdist_wheel' in sys.argv
+version_git = version = '2.1'
 
 if not preparing_PyPI_package:
     if os.path.exists('.git'):
         sha = subprocess.check_output(['git', 'rev-parse', 'HEAD']).decode('ascii').strip()
         version_git = version_git + '+' + sha[:7]
 
-    with open('tensorboardX/__init__.py', 'a') as f:
-        f.write('\n__version__ = "{}"\n'.format(version_git))
+with open('tensorboardX/__init__.py', 'a') as f:
+    f.write('\n__version__ = "{}"\n'.format(version_git))
 
 requirements = [
     'numpy',
@@ -88,10 +89,9 @@ def run(self):
 
 
 # checklist: update History.rst readme.md
-# change preparing_PyPI_package to True, and update version_git to new version
-# remove __version__ = "1.old" in __init__.py, update the version number
+# update the version number in this file.
 # python setup.py sdist bdist_wheel --universal
-# check the generated tar.gz file
+# check the generated tar.gz file (the version, no *.pyc)
 # git add [files]
 # git commit -m 'prepare for release'
 # add tag
diff --git a/tensorboardX/__init__.py b/tensorboardX/__init__.py
index 40867323..18025721 100644
--- a/tensorboardX/__init__.py
+++ b/tensorboardX/__init__.py
@@ -5,4 +5,7 @@
 from .torchvis import TorchVis
 from .writer import FileWriter, SummaryWriter
 from .global_writer import GlobalSummaryWriter
-__version__ = "2.0"  # will be overwritten if run setup.py
+__version__ = "dev" 
+# will be overwritten if run setup.py
+# specifically, `python setup.py install` creates [version in setup.py + git SHA hash]
+# python setup.py sdist creates a decimal version number
\ No newline at end of file