[BUG]: Restore breaks when increasing wal.maxParallel to 8.

Environment

Kubernetes 1.32
CNPG Version: 1.26.1
Plugin Barman Cloud Version: 0.6.0

Observation:

We verify our CNPG Backups nightly by restoring them. Thats when we noticed that most backups can not be restored. When decreasing wal.maxParallel from 8 to 1 in the objectstore it works as expected again. Even previously failed attempts to verify a backup work again.

Sample objectstore configuration:

apiVersion: barmancloud.cnpg.io/v1
kind: ObjectStore
metadata:
  name: fah-db-backup
  namespace: kimi
spec:
  configuration:
    data:
      compression: gzip
    destinationPath: s3://XXX/db
    endpointURL: https://s3.eu-central-1.ionoscloud.com
    historyTags:
      backupRetentionPolicy: keep
    s3Credentials:
      accessKeyId:
        key: accessKey
        name: kimi-s3-backup
      secretAccessKey:
        key: secretKey
        name: kimi-s3-backup
    tags:
      backupRetentionPolicy: expire
    wal:
      compression: gzip
      maxParallel: 1
  instanceSidecarConfiguration:
    env:
    - name: AWS_REQUEST_CHECKSUM_CALCULATION
      value: when_required
    - name: AWS_RESPONSE_CHECKSUM_VALIDATION
      value: when_required
    retentionPolicyIntervalSeconds: 1800
  retentionPolicy: 30d

Here an example of trying to restore a backup:

apiVersion: postgresql.cnpg.io/v1
kind: Cluster
metadata:
  labels:
    cnpg-backup-verification: "true"
    original-cluster: fah-db
  name: fah-db-verify-post-barman
  namespace: kimi
spec:
  storage:
    size: 10Gi
  bootstrap:
    recovery:
      database: kf-fah
      owner: kf-fah
      secret:
        name: fah-db-owner-secret
      source: fah-db
  env:
  - name: AWS_REQUEST_CHECKSUM_CALCULATION
    value: when_required
  - name: AWS_RESPONSE_CHECKSUM_VALIDATION
    value: when_required
  externalClusters:
  - name: fah-db
    plugin:
      enabled: true
      isWALArchiver: false
      name: barman-cloud.cloudnative-pg.io
      parameters:
        barmanObjectName: fah-db-backup
        serverName: fah-db

Attached is the complete log of the plugin-barman-cloud sidecar in the CNPG full-recovery job. The critical problem seems to be "end of wal reached" which occurs when restoring with maxParallel 8 but not with maxParallel 1.

plugin_barman_cloud.log

Expectation

Restore works independently of the maxParallel setting.

首先使用提供的 ObjectStore 和 Cluster 配置复现恢复，然后检查 plugin-barman-cloud sidecar 日志中 "end of wal reached" 错误附近的内容。跟踪恢复路径对 wal.maxParallel 的处理，并比较设置为 1 和 8 时的行为；当备份恢复不受该设置影响且能够成功时，即视为完成。