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Welcome to Tibero GTS!

open error.: Too many open files Response Measures

Document Type | Troubleshooting

Category | Admnistration

Applicable Product Versions | 5SP1FS01, 5SP1FS02, 5SP1FS03, 5SP1FS04, 5SP1FS06, 6FS01, 6FS02, 6FS03, 6FS04, 6FS05, 6FS06, 6FS07, 6FS07PS, 7FS01, 7FS02, 7FS02PS

Document Number | TADTS052

 

Issue

During Tibero startup and operation, an open error occurred with the following message.

open error.: Too many open files
This message occurs when the number of file descriptors that a process can open exceeds the system configuration value.
 
 
 
 

Cause

In the installation guide for Tibero versions 6 and below, the default nofile setting for the account is as follows:
  • Soft limit: 1024
  • Hard limit: 2048
If this setting is maintained and over time the number of data files gradually increases, it may exceed the configured nofile value, causing errors.
For example, if the soft limit is set to 1024, adding about 100 data files can reproduce the error.

 

Test Method

Below is an example where open error.: Too many open files occurs.

BEGIN
 FOR i IN 1..100 LOOP
   EXECUTE IMMEDIATE 'ALTER TABLESPACE usr ADD DATAFILE SIZE 1M';
 END LOOP;
END;


***********************************************************************
* Warning:
* Current maximum number of open files = 1024
* Required maximum number of open files for Tibero process = 1026
Recommend adjusting maximum number of open files.
***********************************************************************

***********************************************************************
* Warning:
* Current maximum number of open files = 1024
* Required maximum number of open files for Tibero process = 1036
Recommend adjusting maximum number of open files.
***********************************************************************

 

 

Solutions

If an error caused by nofile limits occurs during Tibero operation, it can be addressed as follows.
 

1. Permanent Measure

Modify the /etc/security/limits.conf file and then restart the database.
 

2. Temporary Measure

You can dynamically modify it using the prlimit command. However, this method resets upon process restart, so it is a temporary solution.
 
If restarting is difficult, you can dynamically adjust the file descriptor limit of the running process using the prlimit command.
 


1. Check current settings

prlimit -p <PID>


2. Example output

[tibero@mtdb01 ~]$ prlimit -p 96653
RESOURCE DESCRIPTION                         SOFT    HARD    UNITS
NOFILE  max number of open files            1024    4096

 

3. Extend soft limit to hard limit level1

prlimit --pid 96653 --nofile=4096:4096

 

4. Verify changes

[tibero@mtdb01 ~]$ prlimit --pid 96653
RESOURCE DESCRIPTION                         SOFT    HARD    UNITS
NOFILE  max number of open files            4096    4096

 

5. Error example (Insufficient permissions)

[tibero@mtdb01 ~]$ prlimit --pid 96672 --nofile=65530:65530
prlimit: failed to set the NOFILE resource limit: Operation not permitted

If the command fails as above, it must be executed with root privileges.

Note
Since the Tibero process references the account's nofile setting value at startup, even if you change the ulimit value later, it will not apply to processes already running.
 
 


6. Monitoring Method

[root@mtdb01 ~]$ pid=$(ps -ef | grep '[t]bsvr' | awk 'NR==1 {print $2}'); limit=$(prlimit -p $pid | awk '/NOFILE/ {print $(NF-1)}'); used=$(ps -ef | grep 'tbsvr' | grep -v grep | awk '{print $2}' | xargs -I {} sh -c 'ls -1 /proc/{}/fd 2>/dev/null | wc -l' | awk '{sum+=$1} END{print sum}'); available=$((limit - used)); threshold=$((limit * 5 / 100)); usage_percent=$((used * 100 / limit)); echo -e "\n\nFD Limit: $limit, Used: $used, Available: $available, Threshold(5%): $threshold, Usage: ${usage_percent}%"; [ $available -lt $threshold ] && echo " Available FD is less than 5% of total." || echo "  Available FD is sufficient."
You can use the following command to check if the FD value is insufficient.
 
If AVAILABLE is close to 0, and 
Usage is close to 100, it means FD value adjustment is necessary.

 

 

Meaning

Description

FD LIMIT

Maximum number of file descriptors (FD) allowed
 		The maximum number of files, sockets, pipes, etc. that the process (tbsvr) can open.
In Linux, can be checked with ulimit -n or prlimit commands.
Files beyond this cannot be opened.

Used

Number of file descriptors currently used by tbsvr-related processesThe total number of FDs actually opened by tbsvr-related processes.
That is, the current number of open files/sockets.

Available

Number of FDs still available to open
 		Calculated as FD Limit - Used.
Number of FDs that the system can still open.

Threshold

Warning threshold (5% of total)Represents 5% of the total FD limit.
If the remaining FD (Available) is less than this value when running the command, a "less than 5% warning" message is displayed.
 

Usage

Current usage percentage (%)Calculated as (Used รท Limit) ร— 100.
Shows at a glance how much of the FD limit is currently used.
 

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