fix(tasks): 任务队列 - 限制缓存回源并修复并发租约与过期写入

backend/internal/service/runtime_policy.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -187,8 +188,14 @@ func (s *Service) RuntimePolicy() (RuntimePolicySetting, error) {
 }
 
 func (s *Service) runtimeConcurrencySetting() (RuntimeTaskPolicy, error) {
-	policy, err := s.RuntimePolicy()
-	return policy.Task, err
+	s.initReadCaches()
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	return s.concurrencyReadCache.get(ctx, runtimePolicySettingKey, func(ctx context.Context) (RuntimeTaskPolicy, int, error) {
+		reader := &Service{repo: s.repo.WithContext(ctx)}
+		policy, err := reader.RuntimePolicy()
+		return policy.Task, 256, err
+	})
 }
 
 func (s *Service) PublicRuntimeLimits() (*PublicRuntimeLimits, error) {
@@ -243,6 +250,8 @@ func (s *Service) UpdateRuntimePolicySetting(actor *model.User, value RuntimePol
 	if err := s.repo.SaveSystemSetting(&setting); err != nil {
 		return nil, err
 	}
+	s.initReadCaches()
+	s.concurrencyReadCache.clear()
 	if err := s.appendAdminAudit(actor, "runtime_policy.update", "system_setting", runtimePolicySettingKey, "更新资源与请求策略", map[string]any{"before": before, "after": value}); err != nil {
 		return nil, err
 	}
@@ -260,6 +269,8 @@ func (s *Service) ResetRuntimePolicySetting(actor *model.User) (*PublicRuntimePo
 	if err := s.repo.DeleteSystemSetting(runtimePolicySettingKey); err != nil {
 		return nil, err
 	}
+	s.initReadCaches()
+	s.concurrencyReadCache.clear()
 	after := defaultRuntimePolicy()
 	if err := s.appendAdminAudit(actor, "runtime_policy.reset", "system_setting", runtimePolicySettingKey, "重置资源与请求策略", map[string]any{"before": before, "after": after}); err != nil {
 		return nil, err