diff --git a/filterwidget.py b/filterwidget.py
index 8c1df33..89b3b08 100644
--- a/filterwidget.py
+++ b/filterwidget.py
@@ -1,11 +1,12 @@
 import os
 import re
 import tempfile
+import threading
 import time
-from typing import Optional
+from typing import Optional, Callable
 
 from PyQt6.QtCore import QRunnable, QThreadPool
-from PyQt6.QtWidgets import QWidget, QVBoxLayout, QHBoxLayout, QLineEdit, QCheckBox
+from PyQt6.QtWidgets import QWidget, QVBoxLayout, QHBoxLayout, QLineEdit, QCheckBox, QPushButton
 
 from bigtext import BigText
 from logFileModel import LogFileModel
@@ -19,36 +20,46 @@ class FilterTask(QRunnable):
             self,
             source_model: LogFileModel,
             filter_model: LogFileModel,
-            regex: re.Pattern
+            regex: re.Pattern,
+            lock: threading.RLock,
+            on_before: Callable[[], None],
+            on_finish: Callable[[], None]
     ):
         super(FilterTask, self).__init__()
         self.source_model = source_model
         self.filter_model = filter_model
         self.regex = regex
-        self.future = asyncio.Future()
+        self.on_before = on_before
+        self.on_finish = on_finish
+        self.lock = lock
 
     def run(self):
         # print("writing to tmp file", self.filter_model.get_file())
-        start = time.time()
-        with open(self.source_model.get_file(), "rb") as source:
-            with open(self.filter_model.get_file(), "w+b") as target:
-                while l := source.readline():
-                    line = l.decode("utf8", errors="ignore")
 
-                    if self.regex.findall(line):
-                        target.write(line.encode("utf8"))
+        # the lock ensures that we only start a new search when the previous search already ended
+        with self.lock:
+            self.on_before()
+            try:
+                with open(self.source_model.get_file(), "rb") as source:
+                    with open(self.filter_model.get_file(), "w+b") as target:
+                        while l := source.readline():
+                            line = l.decode("utf8", errors="ignore")
 
-                    if self.aborted or self.future.cancelled():
-                        print("aborted")
-                        break
-        #print("filtering for %s took %s" % (self.regex, time.time() - start))
-        self.future.done()
+                            if self.regex.findall(line):
+                                target.write(line.encode("utf8"))
+
+                            if self.aborted:
+                                #print("aborted ", time.time())
+                                break
+            finally:
+                self.on_finish()
 
 
 class FilterWidget(QWidget):
     future = None
     filter_model: LogFileModel
     filter_task: Optional[FilterTask] = None
+    _lock = threading.RLock()
 
     def __init__(self, source_model: LogFileModel):
         super(FilterWidget, self).__init__()
@@ -60,6 +71,10 @@ class FilterWidget(QWidget):
         self.query_field = QLineEdit()
         self.query_field.textChanged.connect(self.filter_changed)
 
+        self.btn_cancel_search = QPushButton(self.tr("Cancel"))
+        self.btn_cancel_search.setVisible(False)
+        self.btn_cancel_search.pressed.connect(self._cancel_search)
+
         self.ignore_case = QCheckBox(self.tr("ignore case"))
         self.ignore_case.setChecked(True)
         self.ignore_case.stateChanged.connect(self.filter_changed)
@@ -72,6 +87,7 @@ class FilterWidget(QWidget):
         filter_bar.layout = QHBoxLayout(filter_bar)
         filter_bar.layout.setContentsMargins(0, 0, 0, 0)
         filter_bar.layout.addWidget(self.query_field)
+        filter_bar.layout.addWidget(self.btn_cancel_search)
         filter_bar.layout.addWidget(self.ignore_case)
         filter_bar.layout.addWidget(self.is_regex)
 
@@ -83,9 +99,14 @@ class FilterWidget(QWidget):
         self.layout.addWidget(self.hits_view)
 
     def destruct(self):
-        print("cleanup: ", self.tmpfilename)
+        #print("cleanup: ", self.tmpfilename)
         os.remove(self.tmpfilename)
 
+    def _cancel_search(self):
+        if self.filter_task:
+            #print("cancel started ", time.time())
+            self.filter_task.aborted = True
+
     def filter_changed(self):
         query = self.query_field.text()
         ignore_case = self.ignore_case.isChecked()
@@ -93,8 +114,8 @@ class FilterWidget(QWidget):
         if len(query) == 0:
             return
 
-        if self.filter_task:
-            self.filter_task.aborted = True
+        # cancel previous search
+        self._cancel_search()
 
         try:
             flags = re.IGNORECASE if ignore_case else 0
@@ -106,5 +127,15 @@ class FilterWidget(QWidget):
             # query was not a valid regex -> abort
             return
 
-        self.filter_task = FilterTask(self.source_model, self.filter_model, regex)
+
+
+
+        self.filter_task = FilterTask(
+            self.source_model,
+            self.filter_model,
+            regex,
+            self._lock,
+            lambda : self.btn_cancel_search.setVisible(True),
+            lambda : self.btn_cancel_search.setVisible(False)
+        )
         QThreadPool.globalInstance().start(self.filter_task)