sockWrite Failed for select in EWOULDBLOCK check (11)

Products

• DX Unified Infrastructure Management (Nimsoft / UIM)

Issue/Introduction

- Remote Hub unstable
- UIM v20.10
- hub.log throwing sockWrite error

Environment

Release : 9.2.0

Component : UIM - HUB

Cause

- possibly low/diminished bandwidth

Resolution

Remote hub showing sockWrite Failed error:
sockWrite Failed for select in EWOULDBLOCK check (11)

Customer mentioned that on some other hubs, this may have been happening, and the network admins disabled TSO and GRO on the network adapter to alleviate it. Network admins disabled TSO GSO on the Linux machine adapter.

ethtool -K eno16780032
ethtool -k eno16780032
ethtool -K eno16780032 tso off gso off gro off

Customer will contact and work with the network admin for this hub.

This is outside the scope of UIM but seemed to be affecting hub stability.

command output example:
# ethtool -k eno16780032 | grep segmentation

tcp-segmentation-offload: on
        tx-tcp-segmentation: on
        tx-tcp-ecn-segmentation: off [fixed]
        tx-tcp6-segmentation: on
        tx-tcp-mangleid-segmentation: off
generic-segmentation-offload: on
tx-fcoe-segmentation: off [fixed]
tx-gre-segmentation: off [fixed]
tx-ipip-segmentation: off [fixed]
tx-sit-segmentation: off [fixed]
tx-udp_tnl-segmentation: off [fixed]
tx-gre-csum-segmentation: off [fixed]
tx-udp_tnl-csum-segmentation: off [fixed]
tx-sctp-segmentation: off [fixed]

In a similar case where the same sockWrite error was occurring, the customer ultimately found that the errors/performance issues seemed to stem from unexpected bandwidth issues/limitations.

sockWrite Failed for select in EWOULDBLOCK check (11) is a rare occurrence and we have seen only a few cases with the hub/robot throwing that error.

EWOULDBLOCK means that the socket send buffer is full when sending, or that the socket receive buffer is empty when receiving.

In general, this type of network error/issue must be worked in conjunction with a network administrator.