Skip to main content

TDengine Query Performance Testing with JMeter

Background​

In Internet of Things (IoT) and industrial monitoring scenarios, the query performance of a Time Series Database is critical. As a high-performance time-series database, TDengine's query performance directly impacts real-time monitoring, data analysis, and decision-making efficiency.

This document addresses the following issues:

  • How to test TDengine query performance using a standard tool (JMeter).
  • How to simulate real business scenarios for stress testing.
  • How to analyze test results and optimize database configuration.

Target Audience: Developers, test engineers, and IT Operations. This document assumes readers have basic database knowledge but do not require an in-depth understanding of JMeter or TDengine.

Note: This document does not cover TDengine write performance testing or query performance tuning.

Environment Preparation​

Environment List & Driver Download​

Required Environment:

Note: JMeter 5.6.3 supports Java 8 and above.

Verified Environment for This Document:

  • JDK Version: JDK 11 (performance verification)
  • JMeter Version: 5.6.3
  • TDengine Version: 3.4.0.4.enterprise
  • TDengine JDBC Driver: 3.8.1

JDBC Driver Configuration​

After downloading the TDengine JDBC Driver dist package, two configuration methods are available:

  • Method 1: Place into JMeter lib/ext directory (recommended)

    # JMETER_HOME = JMeter install dir, e.g. /opt/apache-jmeter-5.6.3/
    cp taos-jdbcdriver-3.8.1-dist.jar $JMETER_HOME/lib/ext/

  • Method 2: Specify Classpath in JMX file (not recommended, fallback only)

    Configure in the TestPlan element:

    <stringProp name="TestPlan.user_define_classpath">/absolute/path/to/taos-jdbcdriver-3.8.1-dist.jar</stringProp>

Note: Method 1 is strongly recommended for CLI mode.

JDBC Connection Method​

  • Connection Method: WebSocket
  • Driver Class: com.taosdata.jdbc.ws.WebSocketDriver
  • URL Format: jdbc:TAOS-WS://host1:port1,host2:port2,host3:port3/database?params
  • Default Port: 6041
  • Features:
    • ✅ No TDengine client driver required
    • ✅ Multi-endpoint supported (comma-separated, connection-level load balancing)
    • ✅ Auto-reconnection & failover
    • ✅ Good cross-platform compatibility

Note: Multi-endpoint selects a node via the minimum connection count algorithm at connection setup. A single JDBC connection binds to one node for its lifetime — not request-level load balancing.

URL Examples:

# Single endpoint (test env)
jdbc:TAOS-WS://127.0.0.1:6041/test?user=root&password=taosdata&timezone=Asia/Shanghai

# Three endpoints (production, recommended) ⭐
jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?user=root&password=taosdata&timezone=Asia/Shanghai

Performance Test Environment Checklist​

Verify these system settings before performance testing to avoid bottlenecks:

Check ItemRecommended ValueCommand
File handle limit65535ulimit -n
TCP connection optimizationAdjust by concurrencysysctl net.ipv4.tcp_max_tw_buckets
Swap statusDisabledswapon --show or free -h
Swappiness value1–10 (server)sysctl vm.swappiness

Note: See your OS official docs for system tuning. For TDengine server config, refer to taosd Configuration.

Test Data Preparation​

Generate Test Data with taosgen​

Use taosgen to generate smart meter test data.

Create Configuration File​

Sample config taosgen_meters.yaml:

tdengine:
  dsn: taos+ws://root:taosdata@127.0.0.1:6041/test
  drop_if_exists: true
  props: precision 'ms' vgroups 32 cachemodel 'last_row'

schema:
  name: meters
  tbname:
    prefix: d
    count: 1000000
    from: 0
  columns:
    - name: ts
      type: timestamp
      start: 1704067200000  # 2024-01-01
      precision: ms
      step: 60s  # 1-min interval
    - name: current
      type: float
      min: 0
      max: 100
    - name: voltage
      type: int
      expr: '220 * math.sqrt(2) * math.sin(_i)'
    - name: phase
      type: float
      min: 0
      max: 360
  tags:
    - name: location
      type: binary(24)
      values:
        - Beijing
        - Shanghai
        - Guangzhou
        - Shenzhen
        - Chengdu
    - name: group_id
      type: int
      min: 1
      max: 1000000
  generation:
    interlace: 1
    rows_per_table: 100
    rows_per_batch: 10000
    num_cached_batches: 0

jobs:
  insert:
    steps:
      - uses: tdengine/create-super-table
      - uses: tdengine/create-child-table
        with:
          batch:
            size: 100
            concurrency: 10
      - uses: tdengine/insert
        with:
          concurrency: 20

Run Data Generation​

# Generate data from config
taosgen -c taosgen_meters.yaml

Data Scale​

  • Super Table: meters
  • Child Tables: 1,000,000 (d0 ~ d999999)
  • Rows per Child Table: 100
  • Total Rows: 100 million

Note:

  • rows_per_batch = batch write buffer size, not rows per table. No problem if rows_per_batch > rows_per_table.
  • Adjust count and rows_per_table for your needs.

Small-Scale Version​

For quick validation:

schema:
  name: meters
  tbname:
    prefix: d
    count: 10000      # 10k child tables
    from: 0
  generation:
    rows_per_table: 100

Total: 10k tables × 100 rows = 1 million rows, good for quick tests.

CACHEMODEL Cache Settings​

TDengine caches last_row results, which must be set at database creation and strongly affects test results.

CACHEMODEL Parameter:

ValueDescriptionUse Case
noneNo cache (default)Test real disk I/O for last_row
last_rowCache last row per child tableSpeed up LAST_ROW queries
last_valueCache last non-NULL value per columnSpeed up LAST function
bothBoth caches enabledMax cache effect

How to Configure:

-- Create DB with cache (recommended)
CREATE DATABASE test CACHEMODEL 'last_row';

-- Alter existing DB
ALTER DATABASE test CACHEMODEL 'last_row';

-- Show current config
show create database test;

Notes:

  1. Default = none (cache off)
  2. Frequent CACHEMODEL changes may break last/last_row accuracy
  3. Production: use last_row or both
  4. Test behavior:
    • Cache on: last_row tests connection & scheduling
    • Cache off: last_row tests random disk I/O
    • Disk I/O test: use range / full-scan queries

taosgen Example:

tdengine:
  dsn: taos+ws://root:taosdata@127.0.0.1:6041/test
  drop_if_exists: true
  props: precision 'ms' vgroups 32 cachemodel 'last_row'

Docs: TDengine Database Configuration

Minimal Query Test & Result Analysis​

JDBC Connection Configuration​

JMeter Modes​

  • GUI Mode: For editing/debugging only — not for performance testing
  • CLI Mode (recommended): For performance testing, lightweight & stable

All tests use CLI Mode. Edit in GUI by importing the JMX file.

Sample baseline_test.jmx:

<?xml version="1.0" encoding="UTF-8"?>
<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.6.3">
  <hashTree>
    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="TDengine Baseline Test Plan">
      <stringProp name="TestPlan.comments">Baseline test for TDengine database query performance</stringProp>
      <boolProp name="TestPlan.functional_mode">false</boolProp>
      <boolProp name="TestPlan.tearDown_on_shutdown">true</boolProp>
      <boolProp name="TestPlan.serialize_threadgroups">false</boolProp>
      <elementProp name="TestPlan.user_defined_variables" elementType="Arguments" guiclass="ArgumentsPanel" testclass="Arguments" testname="User Defined Variables">
        <collectionProp name="Arguments.arguments"/>
      </elementProp>
    </TestPlan>
    <hashTree>
      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group">
        <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
        <intProp name="ThreadGroup.num_threads">1</intProp>
        <intProp name="ThreadGroup.ramp_time">1</intProp>
        <boolProp name="ThreadGroup.same_user_on_next_iteration">true</boolProp>
        <elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="Loop Controller" testname="Loop Controller">
          <boolProp name="LoopController.continue_forever">false</boolProp>
          <stringProp name="LoopController.loops">100</stringProp>
        </elementProp>
        <boolProp name="ThreadGroup.scheduler">false</boolProp>
        <stringProp name="ThreadGroup.duration"></stringProp>
        <stringProp name="ThreadGroup.delay"></stringProp>
      </ThreadGroup>
      <hashTree>
        <JDBCDataSource guiclass="TestBeanGUI" testclass="JDBCDataSource" testname="JDBC Connection Configuration">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="dbUrl">jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?timezone=Asia/Shanghai</stringProp>
          <stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>
          <stringProp name="username">root</stringProp>
          <stringProp name="password">taosdata</stringProp>
          <stringProp name="poolMax">10</stringProp>
          <stringProp name="connectionAge">0</stringProp>
          <stringProp name="trimInterval">60000</stringProp>
          <boolProp name="preinit">true</boolProp>
          <intProp name="timeout">10000</intProp>
          <stringProp name="queryTimeout">60</stringProp>
          <boolProp name="keepAlive">true</boolProp>
        </JDBCDataSource>
        <hashTree/>

        <JDBCSampler guiclass="TestBeanGUI" testclass="JDBCSampler" testname="Query Latest Data">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="queryType">Select Statement</stringProp>
          <stringProp name="query">SELECT last_row(*) FROM d1001</stringProp>
          <stringProp name="queryTimeout">60</stringProp>
          <stringProp name="resultSetHandler">Count Records</stringProp>
        </JDBCSampler>
        <hashTree/>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

Key Parameters​

ParamDescriptionRecommended Value
dbUrlJDBC URLUpdate IP/port/DB name
driverJDBC Driver ClassFixed: com.taosdata.jdbc.ws.WebSocketDriver
poolMaxMax connections< 200
connectionAgeConnection lifetime (ms)0 (unlimited)
trimIntervalIdle connection cleanup (ms)60000
preinitPre-init pooltrue
timeoutConnect timeout (ms)10000
keepAliveKeep connection alivetrue
queryTimeoutQuery timeout (s)60 (large queries)

Run the Test​

Standard Mode (full report):

# Set JVM memory
export JVM_ARGS="-Xms4g -Xmx4g -XX:MaxMetaspaceSize=256m -XX:+UseG1GC"

# Run CLI test
jmeter -n -t baseline_test.jmx -l baseline_results.jtl

# Generate HTML report
jmeter -g baseline_results.jtl -o baseline_report/

# Open baseline_report/index.html in browser

High-Concurrency Mode (minimize I/O):

Create perf.properties:

jmeter.save.saveservice.latency=false
jmeter.save.saveservice.connect_time=false
jmeter.save.saveservice.idle_time=false
sampleresult.timestamp.start=false
jmeter.save.saveservice.response_code=false
jmeter.save.saveservice.response_message=false
jmeter.save.saveservice.url=false
jmeter.save.saveservice.label=false
jmeter.save.saveservice.thread_name=false
jmeter.save.saveservice.data_type=false
jmeter.save.saveservice.bytes=false
jmeter.save.saveservice.sent_bytes=false
jmeter.save.saveservice.assertions=false
jmeter.save.saveservice.assertion_results_failure_message=false
jmeter.save.saveservice.subresults=false
jmeter.save.saveservice.thread_counts=false
jmeter.save.saveservice.autoflush=false

Run:

# With reduced logging
jmeter -n -t baseline_test.jmx -l result.jtl -q perf.properties

# No JTL at all (recommended for QPS)
jmeter -n -t baseline_test.jmx

Summary Output Example:

summary +    500 in 00:00:01 =  500.2/s Avg:    2 Min:     1 Max:     5 Err:     0 (0.00%) Active: 4
summary +   1000 in 00:00:02 =  500.0/s Avg:    2 Min:     1 Max:     6 Err:     0 (0.00%) Active: 4
summary =   1500 in 00:00:03 =  500.0/s Avg:    2 Min:     1 Max:     6 Err:     0 (0.00%)

JVM Args:

  • -Xms4g -Xmx4g: fixed heap to avoid resizing
  • -XX:MaxMetaspaceSize=256m: metadata space
  • -XX:+UseG1GC: low-latency GC

Analyze Results​

Open baseline_report/index.html.

HTML Report

Key Metrics:

MetricMeaningExample
ThroughputQueries per second (QPS)1850.3/sec
AverageAvg response time15.3ms
90% Line90% requests finished78ms
95% Line95% requests finished95ms
99% Line99% requests finished150ms
Error%Error rate0.002%

Percentile times (90%/95%/99%) better reflect user experience than average.

JDBC Connection Properties​

Basic Example (timezone):

<stringProp name="dbUrl">jdbc:TAOS-WS://127.0.0.1:6041/test?timezone=Asia/Shanghai</stringProp>
<stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>

Common URLs:

ScenarioJDBC URL Example
Test (single)jdbc:TAOS-WS://localhost:6041/test?timezone=Asia/Shanghai
Production (3 nodes)jdbc:TAOS-WS://td1:6041,td2:6041,td3:6041/prod_db?timezone=Asia/Shanghai

See TDengine JDBC Docs for more options.

CSV Parameterized Testing​

CSV parameterization simulates real multi-device / multi-scenario queries.

Use Cases​

  • Query millions of smart meters
  • Test different time ranges
  • Mix aggregation functions
  • Avoid identical requests

Advantages:

  • Simple text data
  • No JMX changes to update data
  • Recycle & share across threads
  • Multi-variable support

Create CSV File​

# Export child table names (remove quotes)
taos -s "SELECT tags tbname FROM test.meters >> './meters.csv'" && sed -i 's/"//g' meters.csv

# Top 1000 only
taos -s "SELECT tags tbname FROM test.meters limit 1000 >> './meters.csv'" && sed -i 's/"//g' meters.csv

head meters.csv

Sample:

tbname
d37
d47
d87
d130
...

JMX Config​

Sample csv_param_test.jmx:

<?xml version="1.0" encoding="UTF-8"?>
<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.6.3">
  <hashTree>
    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="TDengine CSV Param Test" enabled="true">
      <boolProp name="TestPlan.functional_mode">false</boolProp>
      <boolProp name="TestPlan.tearDown_on_shutdown">true</boolProp>
      <boolProp name="TestPlan.serialize_threadgroups">false</boolProp>
    </TestPlan>
    <hashTree>
      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="5min Stress Test" enabled="true">
        <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
        <elementProp name="ThreadGroup.main_controller" elementType="LoopController">
          <boolProp name="LoopController.continue_forever">true</boolProp>
          <stringProp name="LoopController.loops">-1</stringProp>
        </elementProp>
        <stringProp name="ThreadGroup.num_threads">200</stringProp>
        <stringProp name="ThreadGroup.ramp_time">60</stringProp>
        <boolProp name="ThreadGroup.scheduler">true</boolProp>
        <stringProp name="ThreadGroup.duration">300</stringProp>
        <stringProp name="ThreadGroup.delay">0</stringProp>
      </ThreadGroup>
      <hashTree>
        <JDBCDataSource guiclass="TestBeanGUI" testclass="JDBCDataSource" testname="JDBC Config">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="dbUrl">jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?timezone=Asia/Shanghai</stringProp>
          <stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>
          <stringProp name="username">root</stringProp>
          <stringProp name="password">taosdata</stringProp>
          <stringProp name="poolMax">200</stringProp>
          <stringProp name="connectionAge">0</stringProp>
          <stringProp name="trimInterval">60000</stringProp>
          <boolProp name="preinit">true</boolProp>
          <intProp name="timeout">10000</intProp>
          <boolProp name="keepAlive">true</boolProp>
        </JDBCDataSource>
        <hashTree/>

        <CSVDataSet guiclass="TestBeanGUI" testclass="CSVDataSet" testname="CSV Data Set">
          <stringProp name="filename">meters.csv</stringProp>
          <stringProp name="variableNames">table_name</stringProp>
          <stringProp name="delimiter">,</stringProp>
          <boolProp name="ignoreFirstLine">true</boolProp>
          <boolProp name="recycle">true</boolProp>
          <stringProp name="shareMode">shareMode.all</stringProp>
        </CSVDataSet>
        <hashTree/>

        <JDBCSampler guiclass="TestBeanGUI" testclass="JDBCSampler" testname="Param Query">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="queryType">Select Statement</stringProp>
          <stringProp name="query">SELECT last_row(*) FROM ${table_name}</stringProp>
          <stringProp name="queryTimeout">10</stringProp>
        </JDBCSampler>
        <hashTree/>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

CSV Config:

ParamDescriptionRecommend
filenameCSV pathAbsolute/relative
variableNamesVariable namesMatch CSV columns
ignoreFirstLineSkip headertrue
recycleLoop datatrue
shareModeThread sharingshareMode.all

Parameterization Scenarios​

Multi-Device Query​

CSV:

table_name
d0
d1
d2

Query:

SELECT last_row(*) FROM ${table_name}

Time-Range Query​

CSV:

hours
1h
6h
24h

Query:

SELECT * FROM d1001 WHERE ts > NOW - ${hours}

Aggregation Types​

CSV:

agg_type
avg(current)
max(voltage)
min(phase)

Query:

SELECT ${agg_type} FROM d1001 WHERE ts > NOW - 1h

Run Test​

export JVM_ARGS="-Xms4g -Xmx4g -XX:+UseG1GC"
jmeter -n -t csv_param_test.jmx

Multi-Variable Parameterization​

CSV:

table_name,group_id
d0,1
d1,1
d2,2

JMX:

<CSVDataSet>
  <stringProp name="variableNames">table_name,group_id</stringProp>
</CSVDataSet>

<JDBCSampler>
  <stringProp name="query">SELECT * FROM ${table_name} WHERE group_id = ${group_id}</stringProp>
</JDBCSampler>

Random Parameter Testing​

Random parameters simulate unpredictable real-world query patterns.

Use Cases​

  • Random meter queries
  • Random time ranges
  • Avoid hot-spot queries

JMX Config​

Sample random_param_test.jmx:

<?xml version="1.0" encoding="UTF-8"?>
<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.6.3">
  <hashTree>
    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="TDengine Random Param Test">
    </TestPlan>
    <hashTree>
      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group">
        <intProp name="ThreadGroup.num_threads">200</intProp>
        <intProp name="ThreadGroup.ramp_time">5</intProp>
        <elementProp name="ThreadGroup.main_controller" elementType="LoopController">
          <boolProp name="LoopController.continue_forever">false</boolProp>
          <stringProp name="LoopController.loops">10000</stringProp>
        </elementProp>
      </ThreadGroup>
      <hashTree>
        <JDBCDataSource guiclass="TestBeanGUI" testclass="JDBCDataSource" testname="JDBC Config">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="dbUrl">jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?timezone=Asia/Shanghai</stringProp>
          <stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>
          <stringProp name="username">root</stringProp>
          <stringProp name="password">taosdata</stringProp>
          <stringProp name="poolMax">200</stringProp>
        </JDBCDataSource>
        <hashTree/>

        <JDBCSampler guiclass="TestBeanGUI" testclass="JDBCSampler" testname="Random Query">
          <stringProp name="dataSource">taos</stringProp>
          <stringProp name="query">SELECT * FROM d${__Random(1001,2000)} WHERE ts > NOW - ${__Random(1,24)}h LIMIT 100</stringProp>
        </JDBCSampler>
        <hashTree/>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

Adjust Parameters​

GoalChange
Random table range__Random(1001,2000)
Random time range__Random(1,24)
Result rowsLIMIT 100

Run Test​

export JVM_ARGS="-Xms4g -Xmx4g -XX:+UseG1GC"
jmeter -n -t random_param_test.jmx

Command-Line Property Parameterization​

Parameterize via CLI without editing JMX.

Use Cases​

  • Quick config switching
  • CI/CD automation
  • Batch testing

Basic Usage​

Use ${__P(prop, default)} in JMX.

Sample param_test.jmx:

<?xml version="1.0" encoding="UTF-8"?>
<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.6.3">
  <hashTree>
    <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="TDengine CLI Param Test">
      <elementProp name="TestPlan.user_defined_variables" elementType="Arguments">
        <collectionProp name="Arguments.arguments">
          <elementProp name="THREADS" elementType="Argument">
            <stringProp name="Argument.name">THREADS</stringProp>
            <stringProp name="Argument.value">${__P(threads,10)}</stringProp>
          </elementProp>
          <elementProp name="LOOPS" elementType="Argument">
            <stringProp name="Argument.name">LOOPS</stringProp>
            <stringProp name="Argument.value">${__P(loops,100)}</stringProp>
          </elementProp>
        </collectionProp>
      </elementProp>
    </TestPlan>
    <hashTree>
      <JDBCDataSource guiclass="TestBeanGUI" testclass="JDBCDataSource">
        <stringProp name="dataSource">taos</stringProp>
        <stringProp name="dbUrl">jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?timezone=Asia/Shanghai</stringProp>
        <stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>
        <stringProp name="poolMax">200</stringProp>
      </JDBCDataSource>
      <hashTree/>

      <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup">
        <stringProp name="ThreadGroup.num_threads">${__P(threads,10)}</stringProp>
        <elementProp name="ThreadGroup.main_controller" elementType="LoopController">
          <stringProp name="LoopController.loops">${__P(loops,100)}</stringProp>
        </elementProp>
      </ThreadGroup>
      <hashTree>
        <JDBCSampler guiclass="TestBeanGUI" testclass="JDBCSampler">
          <stringProp name="query">SELECT last_row(*) FROM d${__Random(1,200000)}</stringProp>
        </JDBCSampler>
        <hashTree/>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

Run Different Tests​

# Default: 10 threads × 100 loops
jmeter -n -t param_test.jmx

# 100 threads × 20000 loops
jmeter -n -t param_test.jmx -Jthreads=100 -Jloops=20000

JMeter Functions​

FunctionMeaning
${__P(name, default)}Read JMeter property
${__threadNum}Current thread number
${__machineName}Hostname

Batch Test Script​

Sample batch_test.sh:

#!/bin/bash
echo "=== Batch Concurrency Test ==="

CONFIGS=(
  "10:100:Light"
  "50:100:Medium"
  "100:100:Heavy"
  "200:50:Stress"
)

for cfg in "${CONFIGS[@]}"; do
  IFS=':' read -r threads loops desc <<< "$cfg"
  echo "Running: $desc ($threads threads × $loops loops)"
  export JVM_ARGS="-Xms8g -Xmx8g -XX:+UseG1GC"
  jmeter -n -t param_test.jmx -Jthreads=$threads -Jloops=$loops
done
chmod +x batch_test.sh
./batch_test.sh

Concurrency Configuration Test​

Test system behavior under different loads.

Use Cases​

  • 10 / 50 / 100 / 200 threads
  • Find bottlenecks
  • Determine max safe concurrency

Run Concurrency Tests​

export JVM_ARGS="-Xms8g -Xmx8g -XX:MaxMetaspaceSize=512m -XX:+UseG1GC"

jmeter -n -t param_test.jmx
jmeter -n -t param_test.jmx -Jthreads=50
jmeter -n -t param_test.jmx -Jthreads=100
jmeter -n -t param_test.jmx -Jthreads=200

Step Stress Test​

for threads in 10 50 100 200; do
  echo "Testing $threads threads..."
  jmeter -n -t param_test.jmx -Jthreads=$threads
done

Result Analysis Example​

Threads | Avg RT | 90% RT | QPS  | Error%
--------|--------|--------|------|-------
10      | 15ms   | 20ms   | 650  | 0%
50      | 45ms   | 78ms   | 1100 | 0%
100     | 120ms  | 250ms  | 830  | 0.01%
200     | 450ms  | 800ms  | 440  | 5%
  • 10–50 threads: linear scaling
  • 100 threads: RT rises but errors low
  • 200 threads: bottleneck reached

Recommendation: 50–100 threads for production.

Mixed Scenario Test​

Simulate real mixed query traffic.

Scenario Ratio​

  • 70% real-time (last_row)
  • 25% historical (time range)
  • 5% aggregation (group by)

JMX Config​

Sample mixed_scenario_test.jmx:

<jmeterTestPlan version="1.2" properties="5.0" jmeter="5.6.3">
  <hashTree>
    <TestPlan name="Mixed Query 5min Test"></TestPlan>
    <hashTree>
      <JDBCDataSource name="JDBC Config">
        <stringProp name="dataSource">taos</stringProp>
        <stringProp name="dbUrl">jdbc:TAOS-WS://192.168.1.100:6041,192.168.1.101:6041,192.168.1.102:6041/test?timezone=Asia/Shanghai</stringProp>
        <stringProp name="driver">com.taosdata.jdbc.ws.WebSocketDriver</stringProp>
        <stringProp name="poolMax">100</stringProp>
      </JDBCDataSource>
      <hashTree/>

      <CSVDataSet name="CSV Data">
        <stringProp name="filename">meters.csv</stringProp>
        <stringProp name="variableNames">table_name</stringProp>
        <boolProp name="ignoreFirstLine">true</boolProp>
        <boolProp name="recycle">true</boolProp>
      </CSVDataSet>
      <hashTree/>

      <ThreadGroup name="Mixed Load">
        <intProp name="ThreadGroup.num_threads">100</intProp>
        <intProp name="ThreadGroup.ramp_time">15</intProp>
        <boolProp name="ThreadGroup.scheduler">true</boolProp>
        <stringProp name="ThreadGroup.duration">300</stringProp>
      </ThreadGroup>
      <hashTree>
        <!-- 70% realtime -->
        <ThroughputController name="70% Realtime">
          <intProp name="ThroughputController.style">1</intProp>
          <stringProp name="ThroughputController.percentThroughput">70.0</stringProp>
        </ThroughputController>
        <hashTree>
          <JDBCSampler name="Last Row Query">
            <stringProp name="query">SELECT last_row(*) FROM ${table_name}</stringProp>
          </JDBCSampler>
        </hashTree>

        <!-- 25% history -->
        <ThroughputController name="25% History">
          <stringProp name="ThroughputController.percentThroughput">25.0</stringProp>
        </ThroughputController>
        <hashTree>
          <JDBCSampler name="History Query">
            <stringProp name="query">SELECT * FROM ${table_name} WHERE ts > NOW - 24h LIMIT 1000</stringProp>
          </JDBCSampler>
        </hashTree>

        <!-- 5% aggregation -->
        <ThroughputController name="5% Aggregation">
          <stringProp name="ThroughputController.percentThroughput">5.0</stringProp>
        </ThroughputController>
        <hashTree>
          <JDBCSampler name="Agg Query">
            <stringProp name="query">SELECT location, avg(current), max(voltage)
                                    FROM meters
                                    WHERE ts > NOW - 24h and group_id = ${__Random(1,200)}
                                    PARTITION BY location</stringProp>
          </JDBCSampler>
        </hashTree>
      </hashTree>
    </hashTree>
  </hashTree>
</jmeterTestPlan>

Run & Analyze​

export JVM_ARGS="-Xms8g -Xmx8g -XX:MaxMetaspaceSize=512m -XX:+UseG1GC"
jmeter -n -t mixed_scenario_test.jmx

Sample result:

Scene        | Avg RT | QPS   | %
-------------|--------|-------|-----
Realtime     | 25ms   | 2400  | 70%
History      | 180ms  | 165   | 25%
Aggregation  | 450ms  | 22    | 5%

How to Identify TDengine Bottlenecks​

Judge bottlenecks from JMeter metrics and server stats.

From JMeter Results​

1. QPS Stagnates / Drops:

  • Threads ↑ but QPS flat or down → bottleneck

2. Response Time Surges:

  • 99% line jumps > 500ms → saturation

3. Error Rate Rises:

  • 0.1% and rising → overloaded

From TDengine Server Metrics​

Recommended tools:

  • taosKeeper (built-in metrics exporter)
  • TDinsight (Grafana dashboard)

Key Server Metrics:

  1. CPU: taosd + taosAdapter > 80% → CPU bound
  2. Memory: high RSS / OOM → memory pressure
  3. Disk I/O: util > 80% → storage bottleneck
  4. Network: near bandwidth limit → network bound

Bottleneck Decision Flow​

  1. JMeter: QPS flat, RT up, errors up
  2. Check server: CPU / memory / disk / net
  3. Classify bottleneck
  4. Tune accordingly

Practical Tips​

  • Step pressure: 10 → 50 → 100 → 200 threads
  • Fixed-duration tests (5+ min)
  • Watch for stable QPS

Common Mistakes​

  • Only look at average RT (use percentiles)
  • Chase 0% errors (small errors acceptable at very high concurrency)
  • Draw conclusions from one run (repeat tests)

FAQ & Troubleshooting​

Connection Issues​

1. JDBC Driver Not Found:

Cannot load JDBC driver class 'com.taosdata.jdbc.ws.WebSocketDriver'

Fix:

cp taos-jdbcdriver-*.jar $JMETER_HOME/lib/ext/

2. Connection Timeout:

java.sql.SQLException: TDengine Error: connection timeout

Fix:

  • Check TDengine/taosAdapter status
  • Increase timeout in JMX: <intProp name="timeout">30000</intProp>
  • Use port 6041 (WebSocket), not 6030

3. Too Many Open Files:

java.io.IOException: Too many open files

Fix:

ulimit -n 65535

Performance Issues​

1. OutOfMemoryError:

java.lang.OutOfMemoryError: Java heap space

Fix:

export JVM_ARGS="-Xms8g -Xmx8g -XX:MaxMetaspaceSize=512m -XX:+UseG1GC"

2. Connection Pool Exhausted:

java.sql.SQLException: Timeout waiting for idle connection

Fix:

  • Increase poolMax in JDBC config
  • Tune taosAdapter concurrent limits

3. Query Timeout:

java.sql.SQLException: TDengine Error: query timeout

Fix:

  • Raise queryTimeout
  • Add LIMIT / time-range filters
  • Optimize SQL

References​