diff --git a/h2o/backend/server.py b/h2o/backend/server.py

index d9a166f..c9063f2 100644

--- a/h2o/backend/server.py

+++ b/h2o/backend/server.py

@@ -340,9 +340,8 @@ class H2OLocalServer(object):

# Launch the process

win32 = sys.platform == "win32"

flags = getattr(subprocess, "CREATE_NEW_PROCESS_GROUP", 0) if win32 else 0

- prex = os.setsid if not win32 else None

try:

- proc = subprocess.Popen(args=cmd, stdout=out, stderr=err, cwd=cwd, creationflags=flags, preexec_fn=prex)

+ proc = subprocess.Popen(args=cmd, stdout=out, stderr=err, cwd=cwd, creationflags=flags, start_new_session=True)

except OSError as e:

traceback = getattr(e, "child_traceback", None)

raise H2OServerError("Unable to start server: %s" % e, traceback)

diff --git a/h2o/expr.py b/h2o/expr.py

index 6c6a4c3..6d73046 100644

--- a/h2o/expr.py

+++ b/h2o/expr.py

@@ -158,14 +158,16 @@ class ExprNode(object):

# However, keeping it if this scope refers to an H2OFrame (has `_ex` entry)

return isinstance(ref, dict) and '_ex' not in ref

- referrers = gc.get_referrers(self)

+ # GraalVM change: we don't have referers, assume everything has multiple referers

+ # referrers = gc.get_referrers(self)

# removing frames from the referrers to get a consistent behaviour accross Py versions

# as stack frames don't appear in the referrers from Py 3.7.

# also removing the AST expressions built in astfun.py

# as they keep a reference to self if the lambda itself is using a free variable.

- proper_ref = [r for r in referrers if not (inspect.isframe(r) or is_ast_expr(r) or is_debug_ref(r))]

- ref_cnt = len(proper_ref)

- del referrers, proper_ref

+ # proper_ref = [r for r in referrers if not (inspect.isframe(r) or is_ast_expr(r) or is_debug_ref(r))]

+ # ref_cnt = len(proper_ref)

+ # del referrers, proper_ref

+ ref_cnt = 2

# if this self node is referenced by at least one other node (nested expr), then create a tmp frame

if top == 'frame' or (not top and ref_cnt > 1):

self._cache._id = _py_tmp_key(append=h2o.connection().session_id)