diff --git a/src/main/java/org/codelibs/fess/app/web/admin/badword/AdminBadwordAction.java b/src/main/java/org/codelibs/fess/app/web/admin/badword/AdminBadwordAction.java
index 43a1054f7..36e4692b3 100644
--- a/src/main/java/org/codelibs/fess/app/web/admin/badword/AdminBadwordAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/admin/badword/AdminBadwordAction.java
@@ -24,6 +24,7 @@ import java.io.Reader;
 import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.concurrent.ForkJoinPool;
 
 import javax.annotation.Resource;
 
@@ -285,14 +286,14 @@ public class AdminBadwordAction extends FessAdminAction {
     public HtmlResponse upload(final UploadForm form) {
         validate(form, messages -> {}, () -> asUploadHtml());
         verifyToken(() -> asUploadHtml());
-        new Thread(() -> {
+        ForkJoinPool.commonPool().execute(() -> {
             try (Reader reader = new BufferedReader(new InputStreamReader(form.badWordFile.getInputStream(), getCsvEncoding()))) {
                 badWordService.importCsv(reader);
                 suggestHelper.storeAllBadWords(false);
             } catch (final Exception e) {
                 throw new FessSystemException("Failed to import data.", e);
             }
-        }).start();
+        });
         saveInfo(messages -> messages.addSuccessUploadBadWord(GLOBAL));
         return redirect(getClass());
     }
diff --git a/src/main/java/org/codelibs/fess/app/web/admin/elevateword/AdminElevatewordAction.java b/src/main/java/org/codelibs/fess/app/web/admin/elevateword/AdminElevatewordAction.java
index aa638d8df..ee2378913 100644
--- a/src/main/java/org/codelibs/fess/app/web/admin/elevateword/AdminElevatewordAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/admin/elevateword/AdminElevatewordAction.java
@@ -27,6 +27,7 @@ import java.io.Reader;
 import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.concurrent.ForkJoinPool;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -319,7 +320,7 @@ public class AdminElevatewordAction extends FessAdminAction {
     public HtmlResponse upload(final UploadForm form) {
         validate(form, messages -> {}, () -> asUploadHtml());
         verifyToken(() -> asUploadHtml());
-        new Thread(() -> {
+        ForkJoinPool.commonPool().execute(() -> {
             try (Reader reader = new BufferedReader(new InputStreamReader(form.elevateWordFile.getInputStream(), getCsvEncoding()))) {
                 elevateWordService.importCsv(reader);
                 suggestHelper.deleteAllElevateWord(false);
@@ -327,7 +328,7 @@ public class AdminElevatewordAction extends FessAdminAction {
             } catch (final Exception e) {
                 throw new FessSystemException("Failed to import data.", e);
             }
-        }).start();
+        });
         saveInfo(messages -> messages.addSuccessUploadElevateWord(GLOBAL));
         return redirect(getClass());
     }
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/badword/ApiAdminBadwordAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/badword/ApiAdminBadwordAction.java
index 4f655df20..fe7bf1031 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/badword/ApiAdminBadwordAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/badword/ApiAdminBadwordAction.java
@@ -27,6 +27,7 @@ import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
+import java.util.concurrent.ForkJoinPool;
 import java.util.stream.Collectors;
 
 import javax.annotation.Resource;
@@ -145,14 +146,14 @@ public class ApiAdminBadwordAction extends FessApiAdminAction {
     @Execute
     public JsonResponse<ApiResult> post$upload(final UploadForm body) {
         validateApi(body, messages -> {});
-        new Thread(() -> {
+        ForkJoinPool.commonPool().execute(() -> {
             try (Reader reader = new BufferedReader(new InputStreamReader(body.badWordFile.getInputStream(), getCsvEncoding()))) {
                 badWordService.importCsv(reader);
                 suggestHelper.storeAllBadWords(false);
             } catch (final Exception e) {
                 throw new FessSystemException("Failed to import data.", e);
             }
-        }).start();
+        });
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
     }
 
diff --git a/src/main/java/org/codelibs/fess/app/web/api/admin/elevateword/ApiAdminElevatewordAction.java b/src/main/java/org/codelibs/fess/app/web/api/admin/elevateword/ApiAdminElevatewordAction.java
index d90bc0288..9d12f40c9 100644
--- a/src/main/java/org/codelibs/fess/app/web/api/admin/elevateword/ApiAdminElevatewordAction.java
+++ b/src/main/java/org/codelibs/fess/app/web/api/admin/elevateword/ApiAdminElevatewordAction.java
@@ -28,6 +28,7 @@ import java.io.Writer;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.List;
+import java.util.concurrent.ForkJoinPool;
 import java.util.stream.Collectors;
 
 import javax.annotation.Resource;
@@ -157,14 +158,14 @@ public class ApiAdminElevatewordAction extends FessApiAdminAction {
     @Execute
     public JsonResponse<ApiResult> post$upload(final UploadForm body) {
         validateApi(body, messages -> {});
-        new Thread(() -> {
+        ForkJoinPool.commonPool().execute(() -> {
             try (Reader reader = new BufferedReader(new InputStreamReader(body.elevateWordFile.getInputStream(), getCsvEncoding()))) {
                 elevateWordService.importCsv(reader);
                 suggestHelper.storeAllElevateWords(false);
             } catch (final Exception e) {
                 throw new FessSystemException("Failed to import data.", e);
             }
-        }).start();
+        });
         return asJson(new ApiResult.ApiResponse().status(ApiResult.Status.OK).result());
     }
 
diff --git a/src/main/java/org/codelibs/fess/helper/KeyMatchHelper.java b/src/main/java/org/codelibs/fess/helper/KeyMatchHelper.java
index 368fd480c..759b01077 100644
--- a/src/main/java/org/codelibs/fess/helper/KeyMatchHelper.java
+++ b/src/main/java/org/codelibs/fess/helper/KeyMatchHelper.java
@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.concurrent.ForkJoinPool;
 
 import javax.annotation.PostConstruct;
 
@@ -56,7 +57,7 @@ public class KeyMatchHelper {
     }
 
     public void update() {
-        new Thread(() -> reload(reloadInterval)).start();
+        ForkJoinPool.commonPool().execute(() -> reload(reloadInterval));
     }
 
     public List<KeyMatch> getAvailableKeyMatchList() {
diff --git a/src/main/java/org/codelibs/fess/helper/SearchLogHelper.java b/src/main/java/org/codelibs/fess/helper/SearchLogHelper.java
index 12cda1bda..d69def6a9 100644
--- a/src/main/java/org/codelibs/fess/helper/SearchLogHelper.java
+++ b/src/main/java/org/codelibs/fess/helper/SearchLogHelper.java
@@ -26,6 +26,7 @@ import java.util.Map;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ForkJoinPool;
 import java.util.concurrent.TimeUnit;
 
 import javax.annotation.PostConstruct;
@@ -215,7 +216,7 @@ public class SearchLogHelper {
             e.setUpdatedAt(now);
             return e;
         });
-        new Thread(() -> userInfoBhv.insertOrUpdate(userInfo)).start();
+        ForkJoinPool.commonPool().execute(() -> userInfoBhv.insertOrUpdate(userInfo));
         return userInfo;
     }