本文记录一次工作中遇到 Got minus one from a read call 的处理方式。
排查思路：
首先怀疑可能是连接数达到上限，于是尝试连接数据库：
$ sqlplus / as sysdba
SQL*Plus: Release 12.1.0.2.0 Production on Thu Mar 25 01:25:01 2021
Copyright (c) 1982, 2014, Oracle. All rights reserved.
ERROR:
ORA-00020: maximum number of processes (300) exceeded
Enter user-name:
至此，可确定是由于连接数达到上限引起的故障。
解决方法：
修改参数 processes 的值
先断开部分连接，确保数据库管理员可正常连接数据库。
- 连接数据库
$ sqlplus / as sysdba
SQL*Plus: Release 12.1.0.2.0 Production on Thu Mar 25 01:34:57 2021
Copyright (c) 1982, 2014, Oracle. All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
- 查看当前参数值
SQL> show parameter processes;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 1
db_writer_processes integer 10
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 1000
log_archive_max_processes integer 4
processes integer 300
得知当前 processes 值为 300 。
- 修改参数值
SQL> alter system set processes=1000 scope=spfile;
System altered.
修改 processes 值为 1000 。
如果此时查看，会发现修改并未生效。这是因为 processes 为静态参数，需要重启数据库才会生效。
SQL> show parameter processes;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 1
db_writer_processes integer 10
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 1000
log_archive_max_processes integer 4
processes integer 300
- 重启数据库使修改生效
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup ;
ORACLE instance started.
Total System Global Area 1.6267E+11 bytes
Fixed Size 7653480 bytes
Variable Size 2.5233E+10 bytes
Database Buffers 1.3690E+11 bytes
Redo Buffers 529215488 bytes
Database mounted.
Database opened.
再次查看发现修改已生效：
SQL> show parameter processes;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
aq_tm_processes integer 1
db_writer_processes integer 10
gcs_server_processes integer 0
global_txn_processes integer 1
job_queue_processes integer 1000
log_archive_max_processes integer 4
processes integer 1000