A Software Engineer at XCMG plays a vital role in developing and maintaining software solutions that drive the efficiency and innovation of the company’s engineering machinery and equipment. Your work will directly contribute to the design and implementation of software systems that enhance product functionality, improve user experience, and streamline operations across various teams. As a leader in the construction machinery industry, XCMG relies on skilled software engineers to ensure that their products meet the rigorous demands of modern engineering applications. This position is critical because it combines technical expertise with an understanding of user needs and product performance. You will be involved in a variety of projects, from developing control systems for large machinery to creating user-friendly interfaces for complex engineering software. The impact of your work extends beyond code; it shapes the very essence of how XCMG products integrate cutting-edge technology to meet global standards. In this role, you can expect to work on challenging problems that require innovative solutions. Whether you are collaborating with cross-functional teams to design a new feature or troubleshooting existing systems, your contributions will be essential to the success and reputation of as a leader in the engineering sector. XCMG
Initial Online Interview
reportedThe process begins with an online interview to assess initial qualifications.
What to demonstrate
- The process begins with an online interview to assess initial qualifications
- Depth in PASCAL Law / Pascal’s Principle
How to prepare
- Answer aloud and timed: What programming languages are you most proficient in, and how have you applied them in your previous projects?
- Answer aloud and timed: Can you explain the concept of Pascal’s Law and how it relates to hydraulic systems?
HR Conversation
reportedA discussion with HR to explore candidate fit and company culture.
What to demonstrate
- A discussion with HR to explore candidate fit and company culture
- Depth in PASCAL Law / Pascal’s Principle
How to prepare
- Answer aloud and timed: Describe a time when you had to troubleshoot a complex software issue. What steps did you take?
- Answer aloud and timed: How do you approach performance optimization in your code?
Technical Interviews
reportedCandidates engage in technical assessments with team members to evaluate problem-solving skills.
What to demonstrate
- Candidates engage in technical assessments with team members to evaluate problem-solving skills
- Depth in PASCAL Law / Pascal’s Principle
How to prepare
- Answer aloud and timed: What experience do you have with Version Control Systems like Git?
- Answer aloud and timed: Can you describe the architecture of a software system you have worked on?
PracHub editorial advice for the preparation topics above.
Research the Company
Familiarize yourself with XCMG’s products, services, and recent innovations in the engineering sector. This knowledge will help you articulate your interest in the company and demonstrate your alignment with its goals.
Practice Coding
Brush up on coding skills and algorithms relevant to the position. Utilize online platforms to practice coding challenges and familiarize yourself with common problem types.
Prepare STAR Stories
Use the STAR method (Situation, Task, Action, Result) to structure your answers to behavioral questions. This technique helps you provide clear and concise responses that highlight your contributions.
Engage with Interviewers
During the interview, don’t hesitate to ask thoughtful questions that show your interest in the role and the company culture. This interaction can help you establish rapport with your interviewers.
Choose a category, try a prompt, then open its approach, worked solution or follow-up when you need it.
Write a function that reverses a string. Discuss the time and space complexity of your solution.
Write a function that reverses a string. Discuss the time and space complexity of your solution.
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
How would you implement a simple search algorithm? What are its advantages and disadvantages?
How would you implement a simple search algorithm? What are its advantages and disadvantages?
Approach
- Restate the input: its shape, its size, and what is guaranteed about it.
- Name the brute-force solution and its complexity before improving on it.
- Choose the data structure from the access pattern, not from familiarity.
- State the target complexity and say which constraint rules the naive version out.
Follow-up
- How does this change if the input no longer fits in memory?
- What is the worst case, and how likely is it on real data?
Merge partitioned event streams into one ordered feed with bounded lateness
The read-model service consumes 64 log partitions carrying about 4,000 events per second in total. Each partition is ordered within itself, but partitions drift by up to 30 seconds, and the activity feed must present a tenant's events in occurred_at order. Produce the merge. State its complexity, the buffer it requires in events and in bytes, what happens when one partition is idle, and what you do with an event that arrives after you have already emitted its position. Payloads average 1 KB.
Approach
- Merge with a min-heap over the 64 partition heads keyed on (occurred_at, event_id): O(log P) per event and O(n log P) overall. The tie-break on event_id is what makes the output deterministic when two partitions carry the same millisecond, which matters because the feed is paginated and a non-deterministic order reorders pages under the reader.
- Emitting the heap head is only correct once every partition has produced everything up to that timestamp, so the emit condition is a watermark: the minimum across partitions of the highest occurred_at seen, less the allowed lateness. Events are held until the watermark passes them, which is what turns individually ordered streams into a jointly ordered one.
- Size the buffer from the lateness rather than guessing: 4,000 events per second times 30 seconds is 120,000 buffered events, and at 1 KB each about 120 MB of heap. That number is the real price of the ordering guarantee and belongs in front of whoever asked for it.
- Handle the idle partition explicitly, because it fails the feed rather than corrupting it: a partition with no traffic never advances its own maximum, so the watermark freezes and output stops entirely. Either every partition emits a periodic idle marker carrying the broker's current time, or the watermark falls back to wall clock for a partition silent beyond a threshold.
Follow-up
- The lateness budget is raised to five minutes. What is the new buffer, and what besides memory changes?
- The consumer restarts. Where does it resume from, and what does the feed look like for the first 30 seconds?
Find version gaps and relay lag with window functions
outbox_event holds event_id, aggregate_type, aggregate_id, aggregate_version, event_type, payload, status ('pending','published','dead'), attempts, created_at, published_at. A projection is missing rows and you must decide whether the relay skipped events or the consumer dropped them. Write three queries over the last seven days: one listing every aggregate_id whose published aggregate_version sequence has a hole, one giving per-day counts with a running total, and one returning the newest published event per aggregate. For each, say where the window function is evaluated relative to WHERE and LIMIT. PostgreSQL 16.
Approach
- Gaps: compute lead(aggregate_version) OVER (PARTITION BY aggregate_id ORDER BY aggregate_version) in a subquery, then filter next_version <> aggregate_version + 1 in the outer query. Window functions are evaluated after WHERE, GROUP BY and HAVING and before the outer ORDER BY and LIMIT, so the predicate cannot sit in the same WHERE clause and PostgreSQL 16 has no QUALIFY.
- Say what the seven-day filter does to the answer: it truncates every partition, so the first row per aggregate has no predecessor inside the window and a hole spanning the boundary is invisible. Widen the window, or join to resource.version as the authority for the true maximum.
- Running total: SELECT date_trunc('day', created_at) AS d, count() AS n, sum(count()) OVER (ORDER BY date_trunc('day', created_at) ROWS UNBOUNDED PRECEDING). An aggregate inside a window call is legal because grouping runs before windowing. The grouping key is unique per row here so ROWS and RANGE agree, but write the frame anyway — over ungrouped rows with tied timestamps the default RANGE frame pulls in every peer row and the total jumps.
- Newest per aggregate: DISTINCT ON (aggregate_id) ... ORDER BY aggregate_id, aggregate_version DESC is the cheap PostgreSQL-only form when an index matches that order; row_number() OVER (PARTITION BY aggregate_id ORDER BY aggregate_version DESC) = 1 is the portable form and needs a subquery for the same evaluation-order reason as the gap query.
Follow-up
- Relay failover redelivers events. Does a duplicate break the gap query, and how would you detect one from this table alone?
- Turn the gap check into a continuous monitor rather than a query someone runs after an incident. What does it watch?
Replace offset paging on the resource feed with keyset
resource holds resource_id, tenant_id, owner_user_id, title, body_ref, version, status ('draft','active','archived','deleted'), created_at, updated_at, deleted_at, with an index on (tenant_id, status, updated_at DESC, resource_id DESC). The listing endpoint returns active resources for one tenant, newest update first, 50 per page, today with LIMIT 50 OFFSET n. Tenants reach page 400 and rows are created while they read. Write the keyset query, define what the cursor carries and how it is encoded, and say which part of the index each predicate uses. Assume PostgreSQL 16.
Approach
- Name the two failures separately. OFFSET 20000 makes the server produce and discard 20,000 rows, so page cost grows with depth rather than with page size. Independently, any write that changes how many rows sort above the offset moves the window between two fetches, and the direction decides which anomaly you get: an insert lands at the head of updated_at DESC and pushes already-returned rows down past the boundary, so they are returned a second time; a delete above the offset, or a row whose updated_at is bumped above the cursor, pulls rows up and one is never returned at all. Nothing in the response reveals either.
- Write the seek: WHERE tenant_id = $1 AND status = 'active' AND (updated_at, resource_id) < ($2, $3) ORDER BY updated_at DESC, resource_id DESC LIMIT 50. The row-value comparison is one index range rather than a disjunction, and both columns are NOT NULL, which is what makes that comparison well defined.
- Map each predicate onto the index: tenant_id and status are equality on the leading columns, (updated_at, resource_id) is the range, and the ORDER BY matches the index order so no Sort node appears and the scan stops after 50 rows. The DESC in the definition only matters for mixed directions — a plain ascending btree on the same columns is read backwards for this query.
- Put both sort columns in the cursor and nothing the client can tamper with into another tenant: base64 of (updated_at, resource_id), validated server-side, with tenant_id taken from the principal.
Follow-up
- The client asks for 'jump to page 400'. What do you offer instead, and what does the honest version cost?
- Sort order becomes user-selectable across four columns. How many indexes is that, and which would you refuse to add?
What programming languages are you most proficient in, and how have you applied them in your previous projects
What programming languages are you most proficient in, and how have you applied them in your previous projects?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Can you explain the concept of Pascal’s Law and how it relates to hydraulic systems?
Can you explain the concept of Pascal’s Law and how it relates to hydraulic systems?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
How do you approach performance optimization in your code?
How do you approach performance optimization in your code?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
What experience do you have with Version Control Systems like Git?
What experience do you have with Version Control Systems like Git?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Can you describe the architecture of a software system you have worked on?
Can you describe the architecture of a software system you have worked on?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
How would you design a software solution for monitoring and controlling machinery?
How would you design a software solution for monitoring and controlling machinery?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
What considerations do you take into account regarding scalability and reliability in your designs?
What considerations do you take into account regarding scalability and reliability in your designs?
Approach
- Fix the scope first: who calls this, how often, and what they do when it fails.
- Name the read and write paths separately; they rarely have the same bottleneck.
- Choose a partition key and say what query it makes expensive.
- State the consistency you need, and where you are willing to be stale.
Follow-up
- What breaks first when traffic grows ten times?
- How does this behave when that dependency is down for an hour?
Given a scenario where a machine’s control system fails, how would you go about diagnosing the issue?
Given a scenario where a machine’s control system fails, how would you go about diagnosing the issue?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
If tasked with improving an existing software application, what steps would you take to gather requirements an
If tasked with improving an existing software application, what steps would you take to gather requirements and implement changes?
Approach
- Clarify what is being asked and what a complete answer contains.
- State your assumptions explicitly before working the problem.
- Say what you would check first and why it is the highest-information step.
- Work from the requirement backwards to the design.
Follow-up
- What assumption would you test first?
- How would you know your answer was wrong?
Listing latency scales with page size, not with filters
The tenant listing endpoint reads resource filtered by tenant_id and status, ordered by updated_at DESC, and returns each row plus the owner's display name from app_user and the actor of that resource's latest resource_revision. p99 is 55 ms at 10 rows per page and 1.4 s at 200. Database telemetry shows 401 statements per request, each under 1 ms, and nothing in the slow-query log. Diagnose the cause and give the fix, stating the statement count per request and the p99 you expect afterwards.
Approach
- Read the counters before forming a theory. 401 statements for 200 rows is one driver query plus two per row, and sub-millisecond execution with an empty slow-query log rules out a bad plan. The time is round trips, which is why it is invisible in every per-query metric and scales with rows returned rather than with filter selectivity.
- Name the two per-row statements from their normalised text: a single-row app_user lookup by user_id, and a resource_revision lookup by resource_id ordered by version DESC LIMIT 1. Confirm by dropping those two response fields and watching the statement count fall to one. That locates the calls in the serialisation layer, not the repository.
- Check that the arithmetic accounts for the whole gap. Measure one round trip to the replica in isolation; 400 trips at roughly 3 ms of network plus 0.2 ms of execution is about 1.3 s on top of a 55 ms baseline, which matches. If the multiplication had fallen short, the N+1 would only be part of the story and you would keep looking.
- Batch both lookups. Collect owner_user_ids and resource_ids from the driver query, then issue WHERE tenant_id = $1 AND user_id = ANY($2) for the users, and PostgreSQL's SELECT DISTINCT ON (resource_id) ... WHERE resource_id = ANY($2) ORDER BY resource_id, version DESC for the latest revision, which the UNIQUE (resource_id, version) index serves directly. On an engine without DISTINCT ON, use a lateral join or a row_number window. Three statements per request at any page size.
Follow-up
- The page size is capped at 200 today. What breaks first if it is raised to 2,000, and is it still this bug?
- How do you stop the next N+1 from reaching production, given that no individual query is slow and the endpoint's tests pass?
Built from the rounds and topics XCMG candidates report.
Prepare, practise & reflect
One practical outcome each day. Spend longer where you need it.
0 / 7 done01Map the XCMG loop
- Write out the reported sequence: Initial Online Interview, HR Conversation, Technical Interviews.
- For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.
Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.
02Work PASCAL Law / Pascal’s Principle
- Spend the session on PASCAL Law / Pascal’s Principle, which XCMG candidates report being tested on.
- Write one worked example in PASCAL Law / Pascal’s Principle and time yourself on it.
Deliverable: One timed worked example in PASCAL Law / Pascal’s Principle.
03Work DCV (Directional Control Valve)
- Spend the session on DCV (Directional Control Valve), which XCMG candidates report being tested on.
- Write one worked example in DCV (Directional Control Valve) and time yourself on it.
Deliverable: One timed worked example in DCV (Directional Control Valve).
04Work Hydraulic Systems
- Spend the session on Hydraulic Systems, which XCMG candidates report being tested on.
- Write one worked example in Hydraulic Systems and time yourself on it.
Deliverable: One timed worked example in Hydraulic Systems.
05Answer out loud: Technical / Domain Questions
- Answer aloud, timed: What programming languages are you most proficient in, and how have you applied them in your previous projects?
- Answer aloud, timed: Can you explain the concept of Pascal’s Law and how it relates to hydraulic systems?
Deliverable: Spoken answers to 2 reported Technical / Domain Questions question(s), under time.
06Answer out loud: System Design / Architecture
- Answer aloud, timed: Can you describe the architecture of a software system you have worked on?
- Answer aloud, timed: How would you design a software solution for monitoring and controlling machinery?
Deliverable: Spoken answers to 2 reported System Design / Architecture question(s), under time.
07Answer out loud: Behavioral / Leadership
- Answer aloud, timed: Tell us about a time you faced a significant challenge in a project. How did you handle it?
- Answer aloud, timed: How do you prioritize tasks when working on multiple projects?
Deliverable: Spoken answers to 2 reported Behavioral / Leadership question(s), under time.
Expand any day for tasks and deliverables. Your progress is saved on this device.
Behavioural rounds judge the decision you made and what it cost.
Describe a time when you had to troubleshoot a complex software issue. What steps did you take?
Describe a time when you had to troubleshoot a complex software issue. What steps did you take?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Tell us about a time you faced a significant challenge in a project. How did you handle it?
Tell us about a time you faced a significant challenge in a project. How did you handle it?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
How do you prioritize tasks when working on multiple projects?
How do you prioritize tasks when working on multiple projects?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
Describe a situation where you had to lead a team or project. What was the outcome?
Describe a situation where you had to lead a team or project. What was the outcome?
Approach
- Pick a story where you made the decision, not one where you watched it.
- State the situation in two sentences and spend the rest on the reasoning.
- Give the blast radius: what could have broken, and what you measured.
- Name the disagreement and how you resolved it with evidence.
Follow-up
- What would you do differently if you ran that again?
- How did you know your change caused the improvement?
- 01
Describe a time when you had to troubleshoot a complex software issue. What steps did you take?
- 02
Tell us about a time you faced a significant challenge in a project. How did you handle it?
- 03
How do you prioritize tasks when working on multiple projects?
- 04
Describe a situation where you had to lead a team or project. What was the outcome?
What is the typical interview difficulty for a Software Engineer position at XCMG?
The interview difficulty is generally considered average, with a mix of technical and behavioral questions designed to assess your fit for the role and the company culture.
XCMG Software Engineer candidate reports ↗How much preparation time is typical for candidates?
Candidates should aim to dedicate at least 1-2 weeks of focused preparation time, reviewing relevant technical concepts, practicing coding challenges, and reflecting on past experiences that demonstrate their qualifications.
XCMG Software Engineer candidate reports ↗What differentiates successful candidates at XCMG?
Successful candidates often demonstrate a strong technical foundation, effective problem-solving skills, and a genuine alignment with XCMG’s values and mission. Being able to communicate clearly and collaborate effectively is also crucial.
XCMG Software Engineer candidate reports ↗What is the culture like at XCMG?
The culture at XCMG emphasizes innovation, collaboration, and continuous improvement. Engineers are encouraged to share ideas and work together to solve complex challenges in the engineering sector.
XCMG Software Engineer candidate reports ↗What is the typical timeline from initial screen to offer?
The timeline can vary, but candidates typically receive feedback within a few weeks after the final interview stage. The entire process can take anywhere from 2-4 weeks.
XCMG Software Engineer candidate reports ↗Are there any remote work or hybrid expectations?
While some positions may offer flexibility in work arrangements, candidates should be prepared for in-office collaboration, especially during the onboarding process and in team-oriented roles.
XCMG Software Engineer candidate reports ↗What topics does XCMG test in interviews?
XCMG interviews most often cover Problem Solving, PASCAL Law / Pascal’s Principle, Data Analysis (general), Business Analysis Role Understanding, and DCV (Directional Control Valve). The exact emphasis depends on the specific role you apply for.
XCMG Software Engineer candidate reports ↗Sources & methodology 3 sources ↗
No official company page is cited. Rounds and questions come from candidate reports and PracHub editorial material; each source shows the date it was read.
- 01XCMG Software Engineer candidate reports ↗
Company-reported rounds, questions and FAQ.
Candidate reports · Accessed 2026-09-22 - 02PracHub Software Engineer practice ↗
PracHub practice material, not company-reported.
PracHub page · Accessed 2026-09-22 - 03PracHub preparation framework ↗
PracHub preparation guidance.
PracHub page · Accessed 2026-09-22
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