diff --git a/src/_canary/finder.py b/src/_canary/finder.py
index e2b78cda..098a9200 100644
--- a/src/_canary/finder.py
+++ b/src/_canary/finder.py
@@ -72,6 +72,7 @@ def discover(self, pedantic: bool = True) -> list[AbstractTestGenerator]:
         generators: set[AbstractTestGenerator] = set()
         for root, paths in self.roots.items():
             found, e = config.pluginmanager.hook.canary_discover_generators(root=root, paths=paths)
+            print(found)
             generators.update(found)
             errors += e
             logger.debug(f"Found {len(found)} test files in {root}")
diff --git a/src/_canary/session.py b/src/_canary/session.py
index 5849adf5..9232d118 100644
--- a/src/_canary/session.py
+++ b/src/_canary/session.py
@@ -28,6 +28,7 @@
 from .third_party.lock import LockError
 from .util import cpu_count
 from .util import logging
+from .util import serialize
 from .util.filesystem import find_work_tree
 from .util.filesystem import force_remove
 from .util.filesystem import mkdirp
@@ -283,9 +284,9 @@ def dump_testcases(self) -> None:
                 [case.save() for case in self.cases]
             else:
                 cpus = cpu_count()
-                args = ((case.getstate(), case.lockfile) for case in self.cases)
+                args = ((case.lockfile, case.getstate()) for case in self.cases)
                 pool = multiprocessing.Pool(cpus)
-                pool.imap_unordered(json_dump, args, chunksize=len(self.cases) // cpus or 1)
+                pool.imap_unordered(dump_obj, args, chunksize=len(self.cases) // cpus or 1)
                 pool.close()
                 pool.join()
             index = {case.id: [dep.id for dep in case.dependencies] for case in self.cases}
@@ -326,12 +327,7 @@ def load_testcases(self, ids: list[str] | None = None) -> list[TestCase]:
                     continue
                 # see TestCase.lockfile for file pattern
                 file = self.db.join_path("cases", id[:2], id[2:], TestCase._lockfile)
-                with self.db.open(file) as fh:
-                    try:
-                        state = json.load(fh)
-                    except json.JSONDecodeError:
-                        logger.warning(f"Unable to load {file}!")
-                        continue
+                state = serialize.load(file)
                 state["properties"]["work_tree"] = self.work_tree
                 for i, dep_state in enumerate(state["properties"]["dependencies"]):
                     # assign dependencies from existing dependencies
@@ -677,11 +673,9 @@ def handle_signal(sig, frame):
     raise SystemExit(sig)
 
 
-def json_dump(args):
-    data, filename = args
-    mkdirp(os.path.dirname(filename))
-    with open(filename, "w") as fh:
-        json.dump(data, fh, indent=2)
+def dump_obj(args):
+    filename, obj = args
+    serialize.dump(filename, obj)
 
 
 def prefix_bits(byte_array: bytes, bits: int) -> int:
diff --git a/src/_canary/testcase.py b/src/_canary/testcase.py
index d9b05d3d..3d932893 100644
--- a/src/_canary/testcase.py
+++ b/src/_canary/testcase.py
@@ -41,8 +41,7 @@
 from .status import Status
 from .util import filesystem as fs
 from .util import logging
-from .util._json import safeload
-from .util._json import safesave
+from .util import serialize
 from .util.compression import compress_str
 from .util.executable import Executable
 from .util.filesystem import copyfile
@@ -1419,13 +1418,13 @@ def copy_sources_to_workdir(self) -> None:
 
     def save(self):
         lockfile = self.lockfile
-        safesave(lockfile, self.getstate())
+        serialize.dump(lockfile, self.getstate())
         file = os.path.join(self.working_directory, self._lockfile)
         mkdirp(os.path.dirname(file))
         fs.force_symlink(lockfile, file)
 
     def _load_lockfile(self) -> dict[str, Any]:
-        return safeload(self.lockfile)
+        return serialize.load(self.lockfile)
 
     def refresh(self, propagate: bool = True) -> None:
         try:
@@ -1612,19 +1611,6 @@ def teardown(self) -> None:
                 else:
                     fs.force_remove(file)
 
-    def dump(self, fname: str | IO[Any]) -> None:
-        file: IO[Any]
-        own_fh = False
-        if isinstance(fname, str):
-            file = open(fname, "w")
-            own_fh = True
-        else:
-            file = fname
-        state = self.getstate()
-        json.dump(state, file, indent=2)
-        if own_fh:
-            file.close()
-
     def getstate(self) -> dict[str, Any]:
         """Return a serializable dictionary from which the test case can be later loaded"""
         state: dict[str, Any] = {"type": self.__class__.__name__}
@@ -1924,8 +1910,7 @@ def from_state(state: dict[str, Any]) -> TestCase | TestMultiCase:
 
 
 def from_lockfile(lockfile: str) -> TestCase | TestMultiCase:
-    with open(lockfile) as fh:
-        state = json.load(fh)
+    state = serialize.load(lockfile)
     return from_state(state)
 
 
diff --git a/src/_canary/testinstance.py b/src/_canary/testinstance.py
index 1b874aa0..c20f909c 100644
--- a/src/_canary/testinstance.py
+++ b/src/_canary/testinstance.py
@@ -14,8 +14,7 @@
 from .testcase import TestCase
 from .testcase import TestMultiCase
 from .testcase import from_lockfile as testcase_from_lockfile
-from .util._json import safeload
-from .util._json import safesave
+from .util import serialize
 
 key_type = tuple[str, ...] | str
 index_type = tuple[int, ...] | int
@@ -271,10 +270,10 @@ def gpus(self) -> int:
         return len(self.gpu_ids)
 
     def set_attribute(self, **kwargs: Any) -> None:
-        state = safeload(self.lockfile)
+        state = serialize.load(self.lockfile)
         self.attributes.update(kwargs)
         state["properties"].setdefault("instance_attributes").update(self.attributes)
-        safesave(self.lockfile, state)
+        serialize.dump(self.lockfile, state)
 
     def get_dependency(self, **params: Any) -> "TestInstance | None":
         for dep in self.dependencies:
diff --git a/src/_canary/util/_json.py b/src/_canary/util/_json.py
deleted file mode 100644
index 5b5d78d0..00000000
--- a/src/_canary/util/_json.py
+++ /dev/null
@@ -1,41 +0,0 @@
-import json
-import os
-import time
-from typing import Any
-
-from .filesystem import mkdirp
-from .string import pluralize
-
-
-def safesave(file: str, state: dict[str, Any]) -> None:
-    dirname, basename = os.path.split(file)
-    tmp = os.path.join(dirname, f".{basename}.tmp")
-    mkdirp(dirname)
-    try:
-        with open(tmp, "w") as fh:
-            json.dump(state, fh, indent=2)
-        os.replace(tmp, file)
-    finally:
-        if os.path.exists(tmp):
-            os.remove(tmp)
-
-
-def safeload(file: str, attempts: int = 8) -> dict[str, Any]:
-    delay = 0.5
-    attempt = 0
-    while attempt <= attempts:
-        # Guard against race condition when multiple batches are running at once
-        attempt += 1
-        try:
-            with open(file, "r") as fh:
-                return json.load(fh)
-        except Exception:
-            time.sleep(delay)
-            delay *= 2
-    raise FailedToLoadError(
-        f"Failed to load {file} after {attempts} {pluralize('attempt', attempts)}"
-    )
-
-
-class FailedToLoadError(Exception):
-    pass
diff --git a/src/_canary/util/serialize.py b/src/_canary/util/serialize.py
new file mode 100644
index 00000000..226ed31e
--- /dev/null
+++ b/src/_canary/util/serialize.py
@@ -0,0 +1,51 @@
+import json
+import pickle  # nosec B403
+import time
+from pathlib import Path
+from typing import Any
+
+from .string import pluralize
+
+PICKLE = 0
+JSON = 1
+
+protocol = JSON
+
+
+def dump(file: str | Path, obj: Any) -> None:
+    file = Path(file)
+    file.parent.mkdir(parents=True, exist_ok=True)
+    tmp = file.with_suffix(".tmp")
+    if protocol == JSON:
+        with open(tmp, "w") as fh:
+            json.dump(obj, fh, indent=2)
+    else:
+        with open(tmp, "wb") as fh:
+            pickle.dump(obj, fh)  # nosec B301
+    tmp.replace(file)
+
+
+def load(file: str | Path, attempts: int = 8) -> Any:
+    file = Path(file)
+    delay = 0.5
+    attempt = 0
+    while attempt <= attempts:
+        # Guard against race condition when multiple batches are running at once
+        attempt += 1
+        try:
+            if protocol == JSON:
+                with open(file, "r") as fh:
+                    return json.load(fh)
+            else:
+                with open(file, "rb") as fh:
+                    return pickle.load(fh)  # nosec B301
+        except Exception:
+            time.sleep(delay)
+            delay *= 2
+    raise FailedToLoadError(
+        f"Failed to load {file.name} after {attempts} {pluralize('attempt', attempts)}"
+    )
+
+
+class FailedToLoadError(Exception):
+    pass