diff --git a/pkgs/development/python-modules/dask/default.nix b/pkgs/development/python-modules/dask/default.nix
index 45b6dd7b6e1..8f3e4d08583 100644
--- a/pkgs/development/python-modules/dask/default.nix
+++ b/pkgs/development/python-modules/dask/default.nix
@@ -12,12 +12,14 @@
 , dill
 , pandas
 , partd
+, pytest-xdist
+, withExtraComplete ? false
+, distributed
 }:
 
 buildPythonPackage rec {
   pname = "dask";
   version = "2021.03.0";
-
   disabled = pythonOlder "3.5";
 
   src = fetchFromGitHub {
@@ -27,13 +29,6 @@ buildPythonPackage rec {
     sha256 = "LACv7lWpQULQknNGX/9vH9ckLsypbqKDGnsNBgKT1eI=";
   };
 
-  checkInputs = [
-    pytestCheckHook
-    pytest-rerunfailures
-  ];
-
-  dontUseSetuptoolsCheck = true;
-
   propagatedBuildInputs = [
     bokeh
     cloudpickle
@@ -43,8 +38,20 @@ buildPythonPackage rec {
     pandas
     partd
     toolz
+  ] ++ lib.optionals withExtraComplete [
+    distributed
   ];
 
+  doCheck = false;
+
+  checkInputs = [
+    pytestCheckHook
+    pytest-rerunfailures
+    pytest-xdist
+  ];
+
+  dontUseSetuptoolsCheck = true;
+
   postPatch = ''
     # versioneer hack to set version of github package
     echo "def get_versions(): return {'dirty': False, 'error': None, 'full-revisionid': None, 'version': '${version}'}" > dask/_version.py
@@ -54,21 +61,18 @@ buildPythonPackage rec {
       --replace "cmdclass=versioneer.get_cmdclass()," ""
   '';
 
-  #pytestFlagsArray = [ "-n $NIX_BUILD_CORES" ];
+  pytestFlagsArray = [ "-n $NIX_BUILD_CORES" ];
 
   disabledTests = [
-    "test_argwhere_str"
-    "test_count_nonzero_str"
-    "rolling_methods"  # floating percision error ~0.1*10^8 small
-    "num_workers_config" # flaky
-    "test_2args_with_array[pandas1-darray1-ldexp]"  # flaky
+    "test_annotation_pack_unpack"
+    "test_annotations_blockwise_unpack"
   ];
 
-  meta = {
+  meta = with lib; {
     description = "Minimal task scheduling abstraction";
     homepage = "https://dask.org/";
     changelog = "https://docs.dask.org/en/latest/changelog.html";
-    license = lib.licenses.bsd3;
-    maintainers = with lib.maintainers; [ fridh ];
+    license = licenses.bsd3;
+    maintainers = with maintainers; [ fridh ];
   };
 }
diff --git a/pkgs/development/python-modules/datashader/default.nix b/pkgs/development/python-modules/datashader/default.nix
index 2b11b1ea273..ad5cc8bfb03 100644
--- a/pkgs/development/python-modules/datashader/default.nix
+++ b/pkgs/development/python-modules/datashader/default.nix
@@ -1,9 +1,7 @@
 { lib
 , buildPythonPackage
 , fetchPypi
-, fetchpatch
 , dask
-, distributed
 , bokeh
 , toolz
 , datashape
@@ -15,38 +13,26 @@
 , colorcet
 , param
 , pyct
-, pyyaml
-, requests
-, scikitimage
 , scipy
-, pytest
-, pytest-benchmark
-, flake8
+, pytestCheckHook
 , nbsmoke
 , fastparquet
-, testpath
 , nbconvert
-, pytest_xdist
+, pytest-xdist
+, netcdf4
 }:
 
 buildPythonPackage rec {
   pname = "datashader";
-  version = "0.11.1";
+  version = "0.12.0";
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "b1f80415f72f92ccb660aaea7b2881ddd35d07254f7c44101709d42e819d6be6";
+    sha256 = "sha256-CnV6ne3cbMtoVUBDqXf4n3tlEMzuKp7H8Ju7Qrzn9es=";
   };
-  patches = [ (fetchpatch {
-    # Unpins pyct==0.46 (Sep. 11, 2020).
-    # Will be incorporated into the next datashader release after 0.11.1
-    url = "https://github.com/holoviz/datashader/pull/960/commits/d7a462fa399106c34fd0d44505a8a73789dbf874.patch";
-    sha256 = "1wqsk9dpxnkxr49fa7y5q6ahin80cvys05lnirs2w2p1dja35y4x";
-  })];
 
   propagatedBuildInputs = [
     dask
-    distributed
     bokeh
     toolz
     datashape
@@ -58,30 +44,29 @@ buildPythonPackage rec {
     colorcet
     param
     pyct
-    pyyaml
-    requests
-    scikitimage
     scipy
-    testpath
   ];
 
   checkInputs = [
-    pytest
-    pytest-benchmark
-    pytest_xdist # not needed
-    flake8
+    pytestCheckHook
+    pytest-xdist # not needed
     nbsmoke
     fastparquet
-    pandas
     nbconvert
+    netcdf4
   ];
 
-  # dask doesn't do well with large core counts
-  checkPhase = ''
-    pytest -n $NIX_BUILD_CORES datashader -k 'not dask.array and not test_simple_nested'
-  '';
+  pytestFlagsArray = [
+    "-n $NIX_BUILD_CORES"
+    "datashader"
+  ];
 
-  meta = with lib; {
+  disabledTestPaths = [
+    # 31/50 tests fail with TypeErrors
+    "datashader/tests/test_datatypes.py"
+  ];
+
+  meta = with lib;{
     description = "Data visualization toolchain based on aggregating into a grid";
     homepage = "https://datashader.org";
     license = licenses.bsd3;
diff --git a/pkgs/development/python-modules/distributed/default.nix b/pkgs/development/python-modules/distributed/default.nix
index 372b931bca2..8ce554e6f6b 100644
--- a/pkgs/development/python-modules/distributed/default.nix
+++ b/pkgs/development/python-modules/distributed/default.nix
@@ -20,13 +20,13 @@
 
 buildPythonPackage rec {
   pname = "distributed";
-  version = "2.30.1";
+  version = "2021.3.0";
   disabled = pythonOlder "3.6";
 
   # get full repository need conftest.py to run tests
   src = fetchPypi {
     inherit pname version;
-    sha256 = "1421d3b84a0885aeb2c4bdc9e8896729c0f053a9375596c9de8864e055e2ac8e";
+    sha256 = "sha256-Qn/n4Ee7rXQTxl1X5W+k1rHPkh/SBqPSyquUv5FTw9s=";
   };
 
   propagatedBuildInputs = [
@@ -38,11 +38,11 @@ buildPythonPackage rec {
   doCheck = false;
   pythonImportsCheck = [ "distributed" ];
 
-  meta = {
+  meta = with lib; {
     description = "Distributed computation in Python.";
     homepage = "https://distributed.readthedocs.io/en/latest/";
-    license = lib.licenses.bsd3;
-    platforms = lib.platforms.x86; # fails on aarch64
-    maintainers = with lib.maintainers; [ teh costrouc ];
+    license = licenses.bsd3;
+    platforms = platforms.x86; # fails on aarch64
+    maintainers = with maintainers; [ teh costrouc ];
   };
 }
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index f871e364c05..10d699e9ee1 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -1660,7 +1660,9 @@ in {
 
   datasette = callPackage ../development/python-modules/datasette { };
 
-  datashader = callPackage ../development/python-modules/datashader { };
+  datashader = callPackage ../development/python-modules/datashader {
+    dask = self.dask.override { withExtraComplete = true; };
+  };
 
   datashape = callPackage ../development/python-modules/datashape { };