在中繼搜索中，如果中繼過載，中繼暱稱旁邊將顯示黃色小點。 那就表示下列的負載指標裡，至少有一項被觸發了：

• 由於可用記憶體量偏低導致洋蔥路由發出OOM警訊
• 有任何洋蔥表皮被丟失的情況
• TCP連接埠號被耗盡

請注意，當中繼節點發生負荷超載的情況時，即使負載量降回正常範圍內，也要等72小時後其顯示狀態才會恢復至正常。

若發現您的中繼節點出現負荷超載現象時，麻煩請進行以下處置：

1. 至 https://status.torproject.org/ 查詢「洋蔥路由網路」分類裡的任何已知問題。

2. 請考慮針對網路、記憶體以及中央處理器的使用量，調整sysctl設定。

3. 請考慮啟用MetricsPort以了解實際情況。

調整網路、記憶體以及中央處理器的sysctl設定

TCP連接埠號耗盡

若您遇到TCP連接埠被耗盡的情況，請考慮擴增本地端可用埠號的範圍。 您可藉由此法來調整

# sysctl -w net.ipv4.ip_local_port_range="15000 64000"

或者

# echo 15000 64000 > /proc/sys/net/ipv4/ip_local_port_range

請記住，如上所述，調整的 sysctl在重啟時丟失，而不是永久的。 為了永久有效，需將其添加到 /etc/sysctl.conf 或 /etc/sysctl.d/中的檔案。

MetricsPort

想要了解 Tor 中繼和 Tor 網絡的運行情況，提供並可訪問中繼指標是至關重要的。 從 0.4.6+ 開始，中繼超載資訊被加入到中繼描述符中，但直到 Tor 0.4.7.1-alpha 之後，才提供底層中繼指標的接口：指標接口。

正在啟用 MetricsPort

通過 torrc 配置選項MetricsPort，Tor 提供指標端口的訪問。

重要的是要明白， 對 Tor 網路用戶，公開暴露 Tor MetricsPort 是為危險的，因此該端口默認不啟用，而且其訪問必須受到訪問政策的約束。 因此當開啟這個連接埠時請特別小心謹慎，並且務必在完成除錯後將它關閉。

假設你是運行了 Tor 中繼的伺服器上的唯一用戶。 可以在 torrc 文件中添加以下內容來啟用指標端口：

MetricsPort 127.0.0.1:9035
MetricsPortPolicy accept 127.0.0.1

然後使用以下命令可輕鬆獲取指標：

# curl http://127.0.0.1:9035/metrics

預設為 Prometheus 格式。

注意： 該伺服器上的每個用戶都能夠訪問上述例子中的中繼指標。 通常，可通過MetricsPortPolicy 設置嚴格的訪問政策，並考慮使用作業系統防火牆功能進行深度防禦。

關於 MetricsPort 和MetricsPortPolicy更詳細的解釋，請參閱 tor 的 man 頁面。

MetricsPort 輸出

以下示例為MetricsPort 啟用後生成的輸出（刪去了所有與擁塞控制有關的指標，因為我們仍然需要穩定該接口）：

# HELP tor_relay_connections Total number of opened connections
# TYPE tor_relay_connections gauge
tor_relay_connections{type="OR listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="OR listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="OR listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="OR listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="OR",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="OR",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="OR",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="OR",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Exit",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Exit",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Exit",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Exit",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Socks listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Socks listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Socks listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Socks listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Socks",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Socks",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Socks",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Socks",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Directory listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Directory listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Directory listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Directory listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Directory",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Directory",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Directory",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Directory",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Control listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Control listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Control listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Control listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Control",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Control",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Control",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Control",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Transparent pf/netfilter listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Transparent pf/netfilter listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Transparent pf/netfilter listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Transparent pf/netfilter listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Transparent natd listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Transparent natd listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Transparent natd listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Transparent natd listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="DNS listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="DNS listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="DNS listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="DNS listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Extended OR",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Extended OR",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Extended OR",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Extended OR",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Extended OR listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Extended OR listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Extended OR listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Extended OR listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="HTTP tunnel listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="HTTP tunnel listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="HTTP tunnel listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="HTTP tunnel listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Metrics listener",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Metrics listener",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Metrics listener",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Metrics listener",direction="received",state="opened",family="ipv6"} 0
tor_relay_connections{type="Metrics",direction="initiated",state="opened",family="ipv4"} 0
tor_relay_connections{type="Metrics",direction="initiated",state="opened",family="ipv6"} 0
tor_relay_connections{type="Metrics",direction="received",state="opened",family="ipv4"} 0
tor_relay_connections{type="Metrics",direction="received",state="opened",family="ipv6"} 0
# HELP tor_relay_connections_total Total number of created/rejected connections
# TYPE tor_relay_connections_total counter
tor_relay_connections_total{type="OR listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="OR listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="OR listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="OR listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="OR listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="OR listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="OR",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="OR",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="OR",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="OR",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="OR",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="OR",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Exit",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Exit",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Exit",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Exit",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Exit",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Exit",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Socks listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Socks listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Socks listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Socks listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Socks listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Socks listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Socks",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Socks",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Socks",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Socks",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Socks",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Socks",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Directory listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Directory listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Directory listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Directory listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Directory listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Directory listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Directory",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Directory",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Directory",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Directory",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Directory",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Directory",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Control listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Control listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Control listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Control listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Control listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Control listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Control",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Control",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Control",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Control",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Control",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Control",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Transparent pf/netfilter listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Transparent natd listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="DNS listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="DNS listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="DNS listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="DNS listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="DNS listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="DNS listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Extended OR listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Extended OR listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="HTTP tunnel listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Metrics listener",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Metrics listener",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Metrics listener",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Metrics listener",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Metrics listener",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Metrics listener",direction="received",state="rejected",family="ipv6"} 0
tor_relay_connections_total{type="Metrics",direction="initiated",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Metrics",direction="initiated",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Metrics",direction="received",state="created",family="ipv4"} 0
tor_relay_connections_total{type="Metrics",direction="received",state="created",family="ipv6"} 0
tor_relay_connections_total{type="Metrics",direction="received",state="rejected",family="ipv4"} 0
tor_relay_connections_total{type="Metrics",direction="received",state="rejected",family="ipv6"} 0
# HELP tor_relay_flag Relay flags from consensus
# TYPE tor_relay_flag gauge
tor_relay_flag{type="Fast"} 0
tor_relay_flag{type="Exit"} 0
tor_relay_flag{type="Authority"} 0
tor_relay_flag{type="Stable"} 0
tor_relay_flag{type="HSDir"} 0
tor_relay_flag{type="Running"} 0
tor_relay_flag{type="V2Dir"} 0
tor_relay_flag{type="Sybil"} 0
tor_relay_flag{type="Guard"} 0
# HELP tor_relay_circuits_total Total number of circuits
# TYPE tor_relay_circuits_total gauge
tor_relay_circuits_total{state="opened"} 0
# HELP tor_relay_streams_total Total number of streams
# TYPE tor_relay_streams_total counter
tor_relay_streams_total{type="BEGIN"} 0
tor_relay_streams_total{type="BEGIN_DIR"} 0
tor_relay_streams_total{type="RESOLVE"} 0
# HELP tor_relay_traffic_bytes Traffic related counters
# TYPE tor_relay_traffic_bytes counter
tor_relay_traffic_bytes{direction="read"} 0
tor_relay_traffic_bytes{direction="written"} 0
# HELP tor_relay_dos_total Denial of Service defenses related counters
# TYPE tor_relay_dos_total counter
tor_relay_dos_total{type="circuit_rejected"} 0
tor_relay_dos_total{type="circuit_killed_max_cell"} 0
tor_relay_dos_total{type="circuit_killed_max_cell_outq"} 0
tor_relay_dos_total{type="marked_address"} 0
tor_relay_dos_total{type="marked_address_maxq"} 0
tor_relay_dos_total{type="conn_rejected"} 0
tor_relay_dos_total{type="concurrent_conn_rejected"} 0
tor_relay_dos_total{type="single_hop_refused"} 0
tor_relay_dos_total{type="introduce2_rejected"} 0
# HELP tor_relay_load_onionskins_total Total number of onionskins handled
# TYPE tor_relay_load_onionskins_total counter
tor_relay_load_onionskins_total{type="tap",action="processed"} 0
tor_relay_load_onionskins_total{type="tap",action="dropped"} 0
tor_relay_load_onionskins_total{type="fast",action="processed"} 0
tor_relay_load_onionskins_total{type="fast",action="dropped"} 0
tor_relay_load_onionskins_total{type="ntor",action="processed"} 0
tor_relay_load_onionskins_total{type="ntor",action="dropped"} 0
tor_relay_load_onionskins_total{type="ntor_v3",action="processed"} 0
tor_relay_load_onionskins_total{type="ntor_v3",action="dropped"} 0
# HELP tor_relay_exit_dns_query_total Total number of DNS queries done by this relay
# TYPE tor_relay_exit_dns_query_total counter
tor_relay_exit_dns_query_total 0
# HELP tor_relay_exit_dns_error_total Total number of DNS errors encountered by this relay
# TYPE tor_relay_exit_dns_error_total counter
tor_relay_exit_dns_error_total{reason="success"} 0
tor_relay_exit_dns_error_total{reason="format"} 0
tor_relay_exit_dns_error_total{reason="serverfailed"} 0
tor_relay_exit_dns_error_total{reason="notexist"} 0
tor_relay_exit_dns_error_total{reason="notimpl"} 0
tor_relay_exit_dns_error_total{reason="refused"} 0
tor_relay_exit_dns_error_total{reason="truncated"} 0
tor_relay_exit_dns_error_total{reason="unknown"} 0
tor_relay_exit_dns_error_total{reason="tor_timeout"} 0
tor_relay_exit_dns_error_total{reason="shutdown"} 0
tor_relay_exit_dns_error_total{reason="cancel"} 0
tor_relay_exit_dns_error_total{reason="nodata"} 0
# HELP tor_relay_load_oom_bytes_total Total number of bytes the OOM has freed by subsystem
# TYPE tor_relay_load_oom_bytes_total counter
tor_relay_load_oom_bytes_total{subsys="cell"} 0
tor_relay_load_oom_bytes_total{subsys="dns"} 0
tor_relay_load_oom_bytes_total{subsys="geoip"} 0
tor_relay_load_oom_bytes_total{subsys="hsdir"} 0
# HELP tor_relay_load_socket_total Total number of sockets
# TYPE tor_relay_load_socket_total gauge
tor_relay_load_socket_total{state="opened"} 0
tor_relay_load_socket_total 0
# HELP tor_relay_load_tcp_exhaustion_total Total number of times we ran out of TCP ports
# TYPE tor_relay_load_tcp_exhaustion_total counter
tor_relay_load_tcp_exhaustion_total 0
# HELP tor_relay_load_global_rate_limit_reached_total Total number of global connection bucket limit reached
# TYPE tor_relay_load_global_rate_limit_reached_total counter
tor_relay_load_global_rate_limit_reached_total{side="read"} 0
tor_relay_load_global_rate_limit_reached_total{side="write"} 0

我們來說明一下這幾行文字代表的意義：

tor_relay_load_onionskins_total{type="ntor",action="dropped"} 0

當中繼節點開始出現「丟失」訊息時，通常是中央處理器或記憶體相關的問題造成的。

遺憾的是 Tor 是單線程的 除了 處理“洋蔥皮”時. 所謂的「洋蔥表皮」是指在每條迴路中，需要針對每個「洋蔥包覆層」進行的加解密運算處理。

當 Tor 在針對包覆層進行處理時，會將其運算作業交付給執行緒池負責。 因此當這個執行緒池遇到記憶體或中央處理器資源吃緊的情況時，有可能會開始丟失掉須處理的運算工作，進而觸發了負荷超載狀態。

當您的伺服器運算資源有限時，這種情況就有可能會發生。

tor_relay_exit_dns_error_total{...}

“*_dns_error_total” 領域的任何計數器（成功查詢的除外）都表明可能存在 DNS 相關的問題。 然而，我們在 0.4.7 的發佈週期中意識到，DNS 錯誤的噪音太大，且包含太多的假陽性，不可用於超載報告。 因此，從 0.4.6.9 和 0.4.7.4-alpha 開始，我們不再將其用於此目的。然而，為了便於中繼營運者瞭解中繼發生了什麼，仍然保留了 DNS 指標。

DNS 超時問題和錯誤只適用於出口節點。

tor_relay_load_oom_bytes_total{...}

而 OOM的指示訊息通常是由記憶體造成的。 您的中繼節點可能需要增加記憶體，或者也有可能是有記憶體洩漏的問題。 若您發現洋蔥路由程式有記憶體洩漏的現象，麻煩請將問題通報至洋蔥路由的GitLab，或者是直接寄發電子郵件至洋蔥路由中繼節點的郵件論壇。

洋蔥路由有內建OOM管理模組，當它可用的總記憶體空間使用量達75%時，此訊息就會被觸發。 Thus, let's say tor thinks it can use 2GB in total then at 1.5GB of memory usage, it will start freeing memory. 此時就會被視為是負荷超載狀態。

To estimate the amount of memory it has available, when tor starts, it will use MaxMemInQueues or, if not set, will look at the total RAM available on the system and apply this algorithm:

    if RAM >= 8GB {
      memory = RAM * 40%
    } else {
      memory = RAM * 75%
    }
    /* Capped. */
    memory = min(memory, 8GB) -> [8GB on 64bit and 2GB on 32bit)
    /* Minimum value. */
    memory = max(250MB, memory)

要避免進入負荷超載的狀態，我們建議若是使用64位元的電腦架設中繼節點的話，那至少要安裝2GB的主記憶體。 如果能夠安裝到4GB當然是更好，當然，盡可能的加大記憶體是有利無害的。 Note: If you are running a powerful server with lots of RAM then you might end up in an overloaded state due to the default queue size limit of 8GB even though you still have plenty of RAM unused. Add an appropriate MaxMemInQueues entry to your torrc configuration in that case.

您或許也會發現，Tor 的OOM訊號也有可能會被作業系統觸發。 因為 Tor 在啟動時，會以整個系統所擁有的記憶體總量去估算其可用量，而當系統中已經有執行許多佔用大量記憶體的程式時，它就會耗用掉過多的記憶體空間。 在這種情況下，即使洋蔥路由程式本身沒有偵測到記憶體不足的情況，作業系統也仍會呼叫並觸發洋蔥路由的OOM訊號。

tor_relay_load_socket_total

如果打開的 socket 端口數量接近或等於可用的總數，那麼這就表明，中繼 socket 端口快要用盡了。 解決方式就是增加洋蔥路由行程的ulimit -n設定值。

tor_relay_load_tcp_exhaustion_total

這幾行訊息代表中繼節點已經耗盡TCP連接埠。

請嘗試依照上述方法調整sysctl設定值。

tor_relay_load_global_rate_limit_reached_total

若發現此計數器的數值在短時間內爆增的話，就表示該中繼節點發生擁塞了。 有可能是因為它被某個洋蔥服務站台用作護衛節點，或者是遭受到網路上的分散式阻斷服務攻擊。

若您的中繼節點一直處於負荷超載狀態，且又無法查明原因的話，請聯繫network-report@torproject.org。 您可以利用network-report的OpenPGP金鑰來將郵件加密。